Question

2(a+b) (a-b) - (a-b)²

Answer 1

2(a2-ab+ab-b2 ) - (a2-ab-ab+b2)
2(a2-b2)- (a2-2ab+b2)
2a2-2b2-a2+2ab-b2
a2-b2+2ab 

Answer 2

2(a+b) (a-b) - (a-b)²

(a+b) (a-b) = a²-b²

 (a-b)²= a²-2ab+b²

2( a²-b²)-a²+2ab-b²


2 a²-2b²-a²+2ab-b²

a²-3b²-2ab