find the product of (x-4) (x+5)
You have to use the distributive property:(xx)+(x5)+(-4x)+(-45)x^2+5x-4x-20x^2+x-20
(x-4)(x+5) x^2+5x-4x-20 (Step one: FOIL)x^2+x-20 (Step two: Combine like terms)