Question

Освободитесь от иррациональности в знаменателе.

Answer 1

$frac{7}{2 sqrt{21} } = frac{7* sqrt{21} }{2 sqrt{21}* sqrt{21} } = frac{7 sqrt{21} }{2*21} = frac{7 sqrt{21} }{42}$

$frac{22}{ sqrt{13} - sqrt{2} } = frac{22( sqrt{13} + sqrt{2} )}{( sqrt{13}- sqrt{2})( sqrt{13} + sqrt{2} ) }= frac{22( sqrt{13} + sqrt{2} )}{13-2} = frac{22( sqrt{13} + sqrt{2} )}{11} =2( sqrt{13} + sqrt{2})$