# How do you simplify (x - 5)(x+5)?

Apr 19, 2018

${x}^{2} - 25$

#### Explanation:

This is an example of DOTS: the Difference Of Two Squares.

When we have two brackets where one is pos and one is neg with the same number, we can use this method:

DOTS allows us to cancel any x values, like so:

$\left(x - 5\right) \left(x + 5\right)$
$= {x}^{2} + 5 x - 5 x - 25$

You can see here that due to the signs and the numbers being the same, the $+ 5 x - 5 x$ cancel each other out to equal $0$.

$= {x}^{2} - 25$