Question

factorise : 9x^2-12ax-y^2-z^2-2yz+4a^2

Answer 1

$9 {x}^{2} - 12ax - {y}^{2} - {z}^{2} - 2yz + 4 {a}^{2} \\ = (9 {x}^{2} - 12ax + 4 {a}^{2} ) - ( {y}^{2} + {z}^{2} + 2yz) \\ = {(3x - 2a)}^{2} - {(y + z)}^{2} \\ = (3x - 2a + y + z)(3x - 2a - y - z)$