Simplify:
(xy+yz)2−(xy−yz)2
4xy2z
Using the identity,
(a+b)2=a2+b2+2ab,
we get,
(xy+yz)2=x2y2+y2z2+2xzy2...(1)
Using the identity,
(a−b)2=a2+b2−2ab
we get,
(xy−yz)2=x2y2+y2z2−2xzy2...(2)
Subtracting (2) from (1), we get
(x2y2+y2z2+2xzy2)−(x2y2+y2z2 −2xzy2)
=2xzy2+2xzy2
=4xy2z