第21問答え

次の計算をしなさい。

$$(\sqrt{5} - \sqrt{2})(\sqrt{2}+\sqrt{5})$$

$$3$$

$$ \begin{align} &(\sqrt{5} - \sqrt{2})(\sqrt{2}+\sqrt{5})\\ =&(\sqrt{5} - \sqrt{2})(\sqrt{5}+\sqrt{2})\\ =&5-2=3 \end{align} $$