To multiply or divide radicals, multiply or divide the coefficients and radicands separately: \(x\sqrt{a} \times y\sqrt{b} = xy\sqrt{ab}\) and \({x\sqrt{a} \over y\sqrt{b}} = {x \over y}\sqrt{a \over b}\)
What is \( \frac{18\sqrt{21}}{9\sqrt{3}} \)?
| 2 \( \sqrt{\frac{1}{7}} \) | |
| \(\frac{1}{2}\) \( \sqrt{7} \) | |
| \(\frac{1}{7}\) \( \sqrt{2} \) | |
| 2 \( \sqrt{7} \) |