Question

How do you factor `-4x^2 +11x + 20`?

Answer 1

`-(x-4)(4x+5)`.

Explanation:

Let `P(x)=-4x^2+11x+20`.

We have, `4xx20=4xx4xx5=16xx5, & 16-5=11`. Therefore,

`P(x)=ul(-4x^2+16x)-ul(5x+20)`

`=-4x(x-4)-5(x-4)`

`=(x-4)(-4x-5)`

`=-(x-4)(4x+5)`.