# How do you multiply (x-5)^2?

Mar 18, 2018

${x}^{2} - 10 x + 25$

#### Explanation:

We got: ${\left(x - 5\right)}^{2}$

A fundamental rule in algebra is that ${\left(a - b\right)}^{2} = {a}^{2} - 2 a b + {b}^{2}$, and ${\left(a + b\right)}^{2} = {a}^{2} + 2 a b + {b}^{2}$.

But since we have a minus sign, we use the former one.

So, we plug in $a = x , b = 5$, and we get:

${x}^{2} - 2 \cdot x \cdot 5 + {5}^{2}$

$= {x}^{2} - 10 x + 25$