Question

factorise x²+y²+9z²+2xy+6yz+6xz​

Answer 1

x2-y2-9z2+6yz

x2-y2-(3z) 2+2(y)(3z)

x2-(y-3z) ^2

a^2-b^2=a+b(a-b)

(x-y+3z)(x+y-3z)