Question

Calculați:
$\frac{ \sqrt{45}- \sqrt{75} }{ \sqrt{3} - \sqrt{5} } = ?$
Vă rog, am nevoie urgent, ofer coronița!!!!!

Answer 1

$\displaystyle \frac{ \sqrt{45}- \sqrt{75} }{ \sqrt{3} - \sqrt{5} } = \frac{3 \sqrt{5} -5 \sqrt{3} }{ \sqrt{3} - \sqrt{5} } = \frac{(3 \sqrt{5} -5 \sqrt{3} )( \sqrt{3} + \sqrt{5} )}{3-5} = \\ \\ = \frac{3 \sqrt{15}+15-15-5 \sqrt{15} }{-2} = \frac{-2 \sqrt{15} }{-2} = \sqrt{15}$