Question

Find the value of 4x² + y² + 25x² + 4xy − 10yz − 20zx when x= 4, y = 3 and z = 2.

Answer 1

In the given problem, we have to find value of

Given

We have

This equation can also be written as

Using the identity

${\left(x+y-z\right)}^2=x^2+y^2+z^2+2xy-2yz-2xz$

Hence the value of is .