Question

How do you factor `9x²-6x-15`?

Answer 1

Notice that `15=9+6` hence

`9x^2-6x-(9+6)=9x^2-9-6x-6=9(x^2-1)-6(x+1)= 9(x-1)(x+1)-6(x+1)=(x+1)(9x-9-6)=(x+1)(9x-15)= 3(x+1)(3x-5)`