$$ \begin{aligned}\sqrt{7}\cdot(-5+\sqrt{2})& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-5\sqrt{7}+\sqrt{14}\end{aligned} $$ | |
① | $$ \color{blue}{ \sqrt{7} } \cdot \left( -5 + \sqrt{2}\right) = \color{blue}{ \sqrt{7}} \cdot-5+\color{blue}{ \sqrt{7}} \cdot \sqrt{2} = \\ = - 5 \sqrt{7} + \sqrt{14} $$ |