Tap the blue circles to see an explanation.
| $$ \begin{aligned}7\sqrt{28}-\sqrt{7}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}14\sqrt{7}-\sqrt{7} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}13\sqrt{7}\end{aligned} $$ | |
| ① | $$ 7 \sqrt{28} =
7 \sqrt{ 2 ^2 \cdot 7 } =
7 \sqrt{ 2 ^2 } \, \sqrt{ 7 } =
7 \cdot 2 \sqrt{ 7 } =
14 \sqrt{ 7 } $$ |
| ② | Combine like terms |