Question
Answer
$$3\cdot\dfrac{\sqrt{21}}{\sqrt{7}}=3\sqrt{3}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}3 \cdot \frac{\sqrt{21}}{\sqrt{7}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3 \cdot \frac{7\sqrt{3}}{7} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}3 \cdot \frac{\sqrt{3}}{1} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}3\sqrt{3}\end{aligned} $$ | |
| ① | Multiply in a numerator. $$ \color{blue}{ \sqrt{21} } \cdot \sqrt{7} = 7 \sqrt{3} $$ Simplify denominator. $$ \color{blue}{ \sqrt{7} } \cdot \sqrt{7} = 7 $$ |
| ② | Divide both numerator and denominator by 7. |
| ③ | Remove 1 from denominator. |
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