# How do you simplify 3sqrt5 * sqrt5?

Jun 3, 2016

$15$

#### Explanation:

Don't be confused by what $3 \sqrt{5}$ means. It is just the multiplication of $3$ and $\sqrt{5}$, so $3 \sqrt{5} = 3 \cdot \sqrt{5}$.

Therefore $3 \sqrt{5} \cdot \sqrt{5} = 3 \cdot \sqrt{5} \cdot \sqrt{5}$.

We see that $\sqrt{5} \cdot \sqrt{5} = 5$, so our expression becomes

$3 \sqrt{5} \cdot \sqrt{5} = 3 \cdot \left(\sqrt{5} \cdot \sqrt{5}\right) = 3 \cdot 5 = 15$.