Question

Помогите, пожалуйста

Answer 1

$2sqrt{8a}+0.3sqrt{18a}-4sqrt{200a}=2*2sqrt{2a}+0.3*3sqrt{2a}-4*10sqrt{2a}=\=4sqrt{2a}+0.9sqrt{2a}-40sqrt{2a}=35.1sqrt{2a}$


$(sqrt{7}+sqrt{3})^2=(sqrt{7})^2+2*sqrt{7}*sqrt{3}+(sqrt{3})^2=7+2sqrt{21}+3=10+2sqrt{21}$


$y^2-5=y^2-(sqrt{5})^2=(y-sqrt{5})(y+sqrt{5})$
$a-8=(sqrt{a})^2-(sqrt{8})^2=(sqrt{a}-sqrt{8})(sqrt{a}+sqrt{8})$


$frac{6+sqrt{6}}{2sqrt{6}}=frac{(6+sqrt{6})*sqrt{6}}{2sqrt{6}*sqrt{6}}=frac{6sqrt{6}+6}{12}=frac{sqrt{6}+1}{2}$
$frac{y-3}{sqrt{3}-sqrt{y}}=frac{-((sqrt{3})^2-(sqrt{y})^2)}{sqrt{3}-sqrt{y}}=-frac{(sqrt{3}-sqrt{y})(sqrt{3}+sqrt{y})}{sqrt{3}-sqrt{y}}=-sqrt{3}-sqrt{y}$