Question

x²+4y²+9z²-4xy+12yz-6zx. factorise

Answer 1

x²+4y²+9z²+2(-2xy+6yz-3zx)
=(x-2y-3z)²
(a-b-c)²=a²+b²+c²+2(-ab+bc-ca)

Answer 2

It can be re-written as
=(-x)² + (2y)² + (-3z)² -2(-x)(2y) -2(2y)(-3z) -2(-3z)(-x)

We can observe it is the formula ( a + b + b )²
So, it can be factorized as (-x + 2y -3z)²

Brainliest please ?