Question

express in simplest radical form.
8√5 - √45

Explanation:

Step1: Simplify $\sqrt{45}$

We know that $45 = 9\times5$, so $\sqrt{45}=\sqrt{9\times5}=\sqrt{9}\times\sqrt{5}=3\sqrt{5}$.

Step2: Subtract

The original expression is $8\sqrt{5}-\sqrt{45}$, substituting $\sqrt{45}=3\sqrt{5}$ into it, we get $8\sqrt{5}-3\sqrt{5}=(8 - 3)\sqrt{5}$.

Answer:

$5\sqrt{5}$