Question

cmr

\(^{a^2}\)-\(b^2\)=(a-b)x(a+b)

Answer 1

\(\left(a-b\right)\left(a+b\right)\)

\(=a\left(a+b\right)-b\left(a+b\right)\)

\(=a^2+ab-ba+b^2\)

\(=a^2+b^2\)

Answer 2

Xét vế phải:

(a-b).(a+b) = a(a+b)-b(a+b) = a²+ab-ba+b²=a²+b²

=> đpcm

Answer 3

Douma =)) sai bome

Answer 4

\(\left(a-b\right)\left(a+b\right)\)

\(=a^2+ab-ab-b^2\)

\(=a^2-b^2=VT\)