(x + y)2 - (x - y)2 = ?
A
xy
B
2xy
C
3xy
D
4xy
Correct Answer: 4xy
x+y2-(x-y)2⇒x2+2xy+y2-(x2-2xy+y2)⇒x2+2xy+y2-x2+2xy-y2⇒4xy