1 . Chứng minh :
a, (a-b) (a-b)+2ab= a mũ 2 + b mũ 2
b, ( a + b ) (a + b ) – 2ab = a mũ 2 + b mũ 2
1 . Chứng minh : a, (a-b) (a-b)+2ab= a mũ 2 + b mũ 2 b, ( a + b ) (a + b ) – 2ab = a mũ 2 + b mũ 2
By Gianna
By Gianna
1 . Chứng minh :
a, (a-b) (a-b)+2ab= a mũ 2 + b mũ 2
b, ( a + b ) (a + b ) – 2ab = a mũ 2 + b mũ 2
$(a-b)(a-b)+2ab=a²-ab-ab+b²+2ab=a²+b²$
$(a+b)(a+b)-2ab=a²+ab+ab+b²-2ab=a²+b²$
`(a-b) (a-b)+2ab=a^2+b^2-ab-ab+2ab=a^2+b^2-2ab+2ab=a^2+b^2 (ĐPCM)`
`(a+b) (a+b)-2ab=a^2+b^2+ab+ab-2ab=a^2+b^2-2ab+2ab=a^2+b^2 (ĐPCM)`