Question

21(√7+√2) rationalise the denominator of the following

Answer 1

Answer:

$\frac{21}{ \sqrt{7} + \sqrt{2} }$

$= > \frac{21}{ \sqrt{7} + \sqrt{2} } \times \frac{ \sqrt{7} - \sqrt{2} }{ \sqrt{7} - \sqrt{2} }$

$= > \frac{21 \sqrt{7} - \sqrt{2} }{ ({ \sqrt{7}) }^{2} - { (\sqrt{2}) }^{2} }$

$= > \frac{21 \sqrt{5} }{7 - 2}$

$= > \frac{21 \sqrt{5} }{5}$