Question

How do you factor `x^3-4x^2-36x+144` by grouping?

Answer 1

`x^3-4x^2-36x+144 = (x+6)(x-6)(x-4)`

Explanation:

`x^3-4x^2-36x+144`

= `x^2(x-4)-36(x-4)`

= `(x^2-36)(x-4)`

= `(x^2-6x+6x-36)(x-4)`

= `(x(x-6)+6(x-6))(x-4)`

= `(x+6) (x-6) (x-4)`