math500.com

Factorise x² + 3x - 18	Reason:
= (x + 6)(x - 3) factors	Factorise means to write the expression using factors. Each factor is put in a bracket. (x + 6) and (x - 3) are chosen because +6 and -3 add to +3 (the x coefficient) and they multiply to give -18 (the constant).