Question

15) factorise the follwing- (1) x raiseto2 + x-12

Answer 1

x²+x-12

=x²+(4-3)x-12

=x²+4x-3x-12

x(x+4)-3(x+4)

(x-3)(x+4)

Answer 2

x² + x - 12

=> x² + 4x - 3x - 12 [Here, we have to find the factors of 12, so that the answer of addition comes the middle term and answer of multiplication comes as the last term.]

=> x (x + 4) - 3 (x + 4)

=> (x + 4) (x - 3)

$\therefore{(x^{2} \: + \: x \: - \: 12) \: = \: (x \: + \: 4) \: (x \: - \: 3)}$