Add or subtract by first simplifying each radical and then combining any like radicals. Assume that all variables represent positive numbers.
-$2 \sqrt { 45 }$ - $4 \sqrt {180 }$
A)-$18\sqrt { 5 }$
B)-$30 \sqrt { 5}$
C)$18 \sqrt { 5 }$
D)$30 \sqrt { 5 }$

Question

Quizplus · Accepted Answer

First, simplify each radical: $2\sqrt{45} = 2\sqrt{9 \cdot 5} = 2 \cdot 3\sqrt{5} = 6\sqrt{5}$ and $4\sqrt{180} = 4\sqrt{36 \cdot 5} = 4 \cdot 6\sqrt{5} = 24\sqrt{5}$. Then, $6\sqrt{5} - 24\sqrt{5} = -18\sqrt{5}$.

Add or Subtract by First Simplifying Each Radical and Then 2452 \sqrt { 45 }245​

Add or Subtract by First Simplifying Each Radical and Then $2 \sqrt { 45 }$