[Toán]Toán học cơ bản!

[xoxodetoan]

Có lẻ cơ bản nhất của toán học đại số là những con số va phép toán nhân chia cộng trừ.
Mình lập ra topic mong muốn có thể tích lũy thêm cách tính nhẩm nhanh

I, Phép nhân

1.Nhân với 11
cộng hai số 2 bên rồi cho vào giữa
Ví dụ 16 nhân 11 bằng 176

Có thể mở rộng ra ví dụ như
66 nhân 14 bằng 11 nhân (6 nhân 14) và bằng 924

2.Áp dụng hằng đẳng thức
A bình trư B bình
19 nhân 21 bằng
20-1 nhân 20+ 1 bằng 400-1 bằng 399

3.Áp dụng phương pháp cộng đại số cho 2 số bình phương
21 bình
bằng 20 bình cộng 20 nhân 2 -1 bằng 441
(tổng hai bình phương)

4.Bình phương số 2 chữ số có 5 tận cùng
25 nhân 25 bằng
2 nhân (2+1 )và thêm 25 đường sau bằng 625

5.Phương pháp cộng số hạng ngoai
2002 bình phương bằng
2000 bình cồng 2000 nhân 2 bình và thêm 2bình
bằng 4008004

6.Phương pháp cộng tổng cả hai hạng tử cho số có 2 chữ số:
21 nhân 22 bằng
bằng 20 bình cộng (2+1) nhân 2 cộng 2 nhân 1 bằng 462

[thanhkhoeo]

toán cấp 2 không nên đưa lên đây nhé mà cái này dễ quá có cái nào khác không

[meoconhat1]

thật đó chứ, thấy dễ quá à, pic này mà để vậy bị close sớm thui bạn ạ

[minh_hg]

Chưa đến nỗi close đâu nhưng mà ko kiếm đc cái gì mới mẻ hơn thì cũng sớm đấy c:matrix:

[atlantic_fly]

cho đỡ khô nhé :
cho các kí tự ;9,9,9 +,-,nhân, :
hãy viết thành biểu thức có kết quả là 18

[ܓܨOrion.p0n]

hỏi nè có được đảo số hay hok, với lại phải dùng hết cả các kí tự đó ah :D

[atlantic_fly]

đùa chút thôi mà , bài này cũng chỉ có vậy ,Lâm trả lời đúng rồi

[atlantic_fly]

ví dụ tháng là X , ngày là Y
biểu thức đó ra là 100X +Y =ra 1 số chắc chắn lớn hơn 100
lấy số đó chia cho 100 , thương là tháng , phần dư là ngày sinh

[ܓܨOrion.p0n]

bài này lặp vòng thôi mà
gọi x là tháng sinh của bạn nè:
b2: nhân với 5 được 5x
b3: cộng với 6 được 5x+6
b4: nhân với 4 được 20x+24
b5: cộng với 9 được20x+33
b6: nhân kết quả với 5 được 100x+165
b7: cộng với ngày sinh( lấy là y) được 100x+165+y
b8: lấy kết quả trừ đi 165 còn 100x+y thì ngày sinh là 2 số cuối, còn tháng sinh là số còn lại :D

[ܓܨOrion.p0n]

ơ rứa à, có gì phải nói trước chứ :D, thôi để các e giải trước rồi mềnh chơi vậy :D

[ܓܨOrion.p0n]

đố vui toán đây. ;))
Có 04 đứa rủ nhau đi uống cà phê cóc (Nhung,Thảo,Thu,Thủy),đến lúc tính tiền hết 25.000 đồng. Thảo,Thu,Thủy, ba đứa bỏ tiền mỗi đứa bỏ 10.000 đồng (vậy tổng công là 30.000).Ông chủ quán thối lại 5000. Nhung giữ 2000,đưa lại cho 3 đứa kia mỗi đứa 1000. Vậy tính ra 03 đứa kia mỗi đứa bỏ ra 9000 (9000 x 3 = 27.000),cộng với 2000 Nhung giữ là 29.000,còn một ngàn kia đâu??? Đứa nào lấy???
thấy hay thì thank nhá c:haha:

[ܓܨOrion.p0n]

đây là về toán, hok hề đố mẹo, ai chắc phần toán này sẽ biết ở đâu :heheh:

[letheanh]

Cái 29k đó có ý nghĩa gì đâu. 3 đứa bỏ ra 27k --> nhung cầm phải là (-2k) --> 27+(-2)=25k + 5k ông chủ=30k. Căn bản cái phép tính ở đề bài là vô nghĩa. 29k chẳng là cái quái gì cả

[atlantic_fly]

bài ni lừa người , 2k nhung cầm đã tính rồi lại tính lần nữa nên ra kết quả mâu thuẫn chứ sao
đáng lẽ phải tính 3k của mỗi đứa kia 1k mới đúng
rất vui vì các bạn tnhiệt tình đóng góp cho toppic toán phát huy nhé c:big_smile:

[ܓܨOrion.p0n]

phần hình học không gian, hứng thì làm nhá
chứng minh không tồn tại một khối đa diện có một số lẻ mặt và mỗi mặt có một số lẻ cảnh c:nosebleed:
thấy hay thì thank nhá :D

[xoxodetoan]

c:haha:
Trong bài toán hình lớp 11 ở Soắn 3 : Phép đối xứng trục
Có câu 4.Áp dụng
Có điều rất thú vị.
Ta thấy nếu như thay vào nhúng người vào nước. Mà bằng sách xô nước thì cách thông minh nhất không phải là làm thế nào cho quảng đường AM+MB là ngắn nhất. Mà là chạy thẳng đến vị trị vuông góc giữa điểm B với dòng sông thì chắn chắn đến đích sẽ nhanh hơn!
Các bạn thử giở sách ra mà xem! c:haha:http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg2http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg2http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg3http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg344444http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg2http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg2http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg3http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg344444http://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpghttp://i0006.photobucket.com/albums/0006/findstuff22/Best%20Images/Photography/candycanes2cp-1.jpg.jpg

[NhocS2b12]

tớ có bài này hay hay nè.
cho a,b,c>0 và
a2+b2+c2=1
dùng phương pháp hàm số.CMR
T=a\(b2+c2)+b\(c2+a2)+c\(a2+b2)>=3 căn3\2

[van_anh_hoa]

Đầu tiên chứng minh :
2a\(b^2+c^2)+2b\(c^2+a^2)+2c\(a^2+b^2)=2a\(b^2+c^2 )*2b\(c^2+a^2)*2c\(a^2+b^2)
Sau đó đặt
a\(b^2+c^2)=x
b\(c^2+a^2)=y
c\(a^2+b^2)=z
Ta có :x+y+z=4xyz(1)
Cosi ta có :xyz bé hơn hoặc bằng(x+y+z)^3/27
Thế (1) vào ta có :(x+y+z)bé hơn hoặc bằng (x+y+z)^3* 4/27
.....................>x+y+z bé hơn hoặc bằng 3 căn3\2

[NhocS2b12]

Bạn ơi mình muốn cm bài trên bằng phương pháp hàm số.Mà không đụng tí gì đến bất đẳng thức côsi hay các bdt khác.Bạn thử tìm xem hiểu xem nhé:D

[voimonster]

Bạn ơi bạn chứng minh đi. Mình muốn biết. Môn toán mình hơi kém. c:big_smile:http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/http://photobucket.com/images/scared%20of%20santa/

[NhocS2b12]

Ta có T=a\(1-a2)+b\(1-b2)+c\(1-c2)

xét hàm số f(x)=x(1-x2)với x>0

ta có f '(x)=1-3x2

f '(x)=0 <=>x=1\căn3

lập bảng biến thiên ta có(các bạn học lớp 12 chắc ai cũng biết cách lập)

f(x)<=2\3căn3 với mọi x>0

với a,b,c là nghiệm của pt trên ta có

f(a)=a(1-a2)<=2\3căn3

f(b)=b(1-b2)<=2\3căn3

f(c)=c(1-c2)<=2\3căn3

khi đó T= a2\f(a)+b2\f(b)+c2\f(c)>=3căn3\2*(a2+b2+c2)=3căn3\2