Question

Expand following, using suitable identities :- (–2x + 3y + 2z)² 

 

Answer 1

It is known that,

(x + y + z)² = x² + y² + z² + 2xy + 2yz + 2zx

(–2x + 3y + 2z)² = (-2x)² + (3y)² + (2z)² + 2(-2x)(3y) + 2(3y)(2z) + 2(2z)(-2x)

                          = 4x² + 9y² + 4z² - 12xy + 12yz - 8xz