gimana caranya no 7 makasih

[tex] \frac{3}{5 - \sqrt{2} } \\ = \frac{3}{5 - \sqrt{2}} \times \frac{3}{5 + \sqrt{2} } \\ = \frac{9}{25 + 5 \sqrt{2} - 5 \sqrt{2} - 2} \\ = \frac{9}{23} [/tex]

Semoga bisa membantu :)