To add or subtract radicals, the degree and radicand must be the same. For example, \(2\sqrt{3} + 3\sqrt{3} = 5\sqrt{3}\) but \(2\sqrt{2} + 2\sqrt{3}\) cannot be added because they have different radicands.
What is \( 2 \)\( \sqrt{20} \) - \( 9 \)\( \sqrt{5} \)
| 18\( \sqrt{4} \) | |
| -5\( \sqrt{5} \) | |
| -7\( \sqrt{100} \) | |
| -7\( \sqrt{21} \) |