# How do you factor x²-10x+21?

Nov 18, 2015

${x}^{2} - 10 x + 21 = \left(x - 3\right) \left(x - 7\right)$

#### Explanation:

${x}^{2} - 10 x + 21$

Find two numbers that when added equal $- 10$, and when multiplied equal $21$.

The numbers $- 3$ and $- 7$ meet the criteria.

${x}^{2} - 10 x + 21 = \left(x - 3\right) \left(x - 7\right)$