Question

Упростите выражения.

Answer 1

$2) ( sqrt{6} + sqrt{3})sqrt{12}- 2sqrt{6} * sqrt{3} = sqrt{6*12} + sqrt{3*12}-2 sqrt{6*3}=\= sqrt{72} + sqrt{36} -2sqrt{18}= sqrt{36*2}+6-2 sqrt{9*2} = 6sqrt{2} +6- 6sqrt{2}=\=6\\\3) (frac{6}{y^2-9} + frac{1}{3-y})* frac{y^2+6y+4}{5}=( frac{6}{(y-3)(y+3)} - frac{1}{y-3})* frac{(y+3)^2}{5}=\\=( frac{6 -y-3}{(y-3)(y+3)})* frac{(y+3)^2}{5} = frac{(3-y)(y+3)^2}{5(y-3)(y+3)} = - frac{(y-3)(y+3)}{5(y-3)}= frac{y+3}{5}$