Question

Помогите с выполнением заданий 19,20,21

Answer 1

$1) frac{6+sqrt{6}}{sqrt{30}+sqrt{5}}=frac{(sqrt{6})^{2}+sqrt{6}}{sqrt{6*5}+sqrt{5}}=frac{sqrt{6}(sqrt{6}+1)}{sqrt{5}(sqrt{6}+1)}=frac{sqrt{6}}{sqrt{5}}=frac{sqrt{30}}{5}\\2) frac{4a^{2}+4asqrt{b}+b}{4a^{2}-b} =frac{(2a)^{2}+4asqrt{b}+(sqrt{b})^{2}}{(2a)^{2}-(sqrt{b})^{2}}=frac{(2a+sqrt{b})^{2}}{(2a-sqrt{b})(2a+sqrt{b})}=frac{2a+sqrt{b}}{2a-sqrt{b}}$

$3) x^{2} =sqrt{sqrt{10}-3}*sqrt{sqrt{10}+3}\\x^{2} =sqrt{(sqrt{10}-3)(sqrt{10}+3)} \\x^{2} =sqrt{10-9}\\x^{2} =1 \\x_{1}=1\\x_{2}=-1 \\ frac{S}{t}=frac{1}{v}+2\\frac{S}{t}=frac{1+2v}{v}\\t=frac{S*v}{1+2v}$

Answer 2

Спасибо большое!