Example  2

Simplify the expression \(\sqrt {20} + 5\sqrt 5 \).

Upon initial inspection, the expression may appear to already be fully simplified. While the index values are equal, the radicands are not equal. But, notice that \(\sqrt{20}\) is not in its most simplified form.

Step 1: If possible, simplify individual radicals.

\(\begin{align}
 \sqrt {20} + 5\sqrt 5 &= \sqrt {4\cdot 5} + 5\sqrt 5  \\ 
  &= 2\sqrt 5 + 5\sqrt 5  \\ 
 \end{align}\)


Step 2: Collect like terms to simplify the expression.

\(\begin{align}
 2\sqrt 5 + 5\sqrt 5 &= \left( {2 + 5} \right)\sqrt 5  \\ 
  &= 7\sqrt 5  \\ 
 \end{align}\)