Question

Rationalise:1/7+5√2​

Answer 1

$\frac{1}{7 + 5 \sqrt{2} } \\ \\ ( \frac{1}{7 + 5 \sqrt{2} } ) \times ( \frac{7 - 5 \sqrt{2} }{7 - 5 \sqrt{2} } ) \\ \\ = 5 \sqrt{2} - 7$

hope it helps.