Question

Factorise:-

$x ^{2} - bx -(a + 3b)(a + 2b)$

Answer 1

${x}^{2} - bx - (a + 3b)(a + 2b)\\= {x}^{2} - (a + 3b - a - 2b)x - (a + 3b)(a + 2b) \\ = {x}^{2} - (a + 3b)x + (a + 2b)x - (a + 3b)(a + 2b) \\ = x(x - a -3b) + (a + 2b)(x - a - 3b) \\ = (x - a - 3b)(x + a + 2b)$