Simplify (xy+yz)2−2x2y2z and find the value when x=−1,y=1 and z=2.
-3
Simplify (xy+yz)2 using the identity (a+b)2 = a2+ b2+2ab
We get (xy+yz)2=x2y2 + y2z2 + 2xzy2.
Therefore,
(xy+yz)2 - 2x2y2z = x2y2 + y2z2 + 2xzy2 - 2x2y2z
Placing the values of x,y and z in the above expression we get,
1−4−4−4=−3