# How do you use the zero factor theorem to solve x^2 + 2x - 15?

Apr 9, 2017

#### Explanation:

You use the zero factor theorem to find the results of a quadratic after you have factored it.

For example (From the website above):

${x}^{2} + 2 x - 15 = 0$ factored will give $\left(x - 3\right) \left(x + 5\right) = 0$.

By the definition of the Zero Factor Theorem, we know that one or both of those factors has to equal zero.

Therefore to find the solution to the problem we solve each factor for $0$:

Solution 1 will be found by solving $x - 3 = 0$

Solution 2 will be found by solving $x + 5 = 0$