Question

factorise
$9x ^{2} + 4y ^{2} + 16z ^{2} + 12 \times y - 16yz - 24xz$

Answer 1

$9x^2 + 4y^2 +16z^2 +12xy - 16yz - 24xz \\= (3x)^2 + (2y)^2 + (-4z)^2 + 2(3x)(2y)+2(2y)(-4z) +2(3x)(-4z) \\= (3x + 2y - 4z)^2$

Because (a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ca

Answer 2

9x²+4y²+16z²+12xy-16yz-24xz =(3x+2y-4z)²