Question

Factoring polynomials
2x^2-11x-40

Answer 1

2x^2 - 11x - 40 (multiply 2 and -40, which is -80; find two integers that multiply to -80 but add to -11, which are -16 and 5)
2x^2 - 16x + 5x - 40 (group terms into pairs)
(2x^2 - 16x) + (5x - 40) (factor out from each group)
2x(x - 8) + 5(x - 8) (factor out (x - 8))
(2x + 5)(x - 8)