Y = (xy+yz)2−2x2y2z
When x=−1,y=1 and z=2, |Y| =
3
Y = (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
|Y| = |-3| = 3