=a^2+2ab+b^2-(a^2-2ab+b^2)
=4ab
Học tốt
\(\left(a+b\right)^2-\left(a-b\right)^2\)
\(=\left[a+b-\left(a-b\right)\right]\left[a+b+a-b\right]\)
\(=2b\cdot2a\)
\(=4ab\)
Trả lời:
( a + b )2 - ( a - b )2
= [ ( a + b ) - ( a - b ) ] [ ( a + b ) + ( a - b ) ]
= ( a + b - a + b ) ( a + b + a - b )
= 2b.2a
= 4ab