# How do you expand and simplify f(x) = (x-1)(x+3)(x-5)?

Jun 23, 2016

=${x}^{3} - 3 {x}^{2} - 13 x + 15$

#### Explanation:

Multiply two of the brackets together first, then multiply that answer by the third bracket. You can use any order.
Trying to multiply them all at the same time is very complicated.

$\left(x - 1\right) \left(x + 3\right) \left(x - 5\right)$
=$\left(x - 1\right) \left({x}^{2} - 5 x + 3 x - 15\right) \text{ collect like terms}$
=(x-1))(x^2-2x -15)
=${x}^{3} - 2 {x}^{2} - 15 x - {x}^{2} + 2 x + 15 \text{ collect like terms}$
=${x}^{3} - 3 {x}^{2} - 13 x + 15$