Question

factorise 9 x square - 24 X Y + 16 y square

Answer 1

$9 {x}^{2} - 24xy + 16 {y}^{2} \\ = {(3x)}^{2} - 2 \times 3x \times 4y + {(4y)}^{2} \\ = {(3x - 4y)}^{2} \\ = (3x - 4y)(3x - 4y)$

Identity used:

${(a + b)}^{2} = {a}^{2} - 2 \times a \times b + {b}^{2}$

Where,

$a = 3x \\ b = 4y$