Question

Сократите дробь 
а)
√28-√8
√7 - √2   
б)
√60 + √20
√45+√135
заранее благодарю с:

Answer 1

$a) frac{sqrt{28}-sqrt{8}}{sqrt7-sqrt2}=frac{2sqrt7-2sqrt2}{sqrt7-sqrt2}=frac{2(sqrt7-sqrt2)}{sqrt7-sqrt2}=2.\\ b) frac{sqrt{60}+sqrt{20}}{sqrt{45}+sqrt{135}}=frac{2sqrt{15}+2sqrt5}{3sqrt{5}+3sqrt{15}}=frac{2(sqrt{15}+sqrt5)}{3(sqrt{5}+sqrt{15})}=frac{2}{3}.$