Factor completely 4x2 - 8x - 60

Answer

(4x - 20) (x + 3)

4 (x - 1) (x + 15)

4 (x - 5) (x + 3)

(4x - 4) (x + 15) ... ?

The answer would be 4 (x - 5) (x + 3) ...

To explain further.

First divide the whole equation by 4

4x^2 - 8x - 60

4

Then it will look like 4 (x^2 - 2x - 15)

Then expand the (x^2 - 2x - 15)

and it would be (x - 5) (x + 3)

The shortcut to this expanding is look at the last digit which is - 15, what are the factors that when you add them you'll get - 2? Yes It's (+3, - 5)

Then just put the x