Question

№4. Срочно!.........

Answer 1

a) $3sqrt{2frac{1}{3} } -sqrt{84} -4sqrt{5frac{1}{4} } =\= 3sqrt{frac{7}{3} } -2sqrt{21} -4sqrt{frac{21}{4} } =\= 3*frac{sqrt{7} }{sqrt{3} } -2sqrt{21} -4*frac{sqrt{21} }{2} =\=frac{3sqrt{7} }{sqrt{3} } -2sqrt{21} -2sqrt{21} = sqrt{21} -2sqrt{21} -2sqrt{21} =\ =-3sqrt{21}$

б) $(27b^-^6^)^-^frac{2}{3}=(27*frac{1}{b^6} )^-^frac{2}{3} = (frac{27}{b^6} )^-^frac{2}{3}=(frac{b^6}{27} )^frac{2}{3}=sqrt[3]{(frac{b^6}{27})^2 } =sqrt[3]{frac{b^6}{27}^2 } =\=(frac{b^2}{3} )^2 = frac{b^4}{9}$

в) $sqrt[5]{frac{a^2sqrt[4]{a^-^3} }{a^-^frac{1}{4}}}= sqrt[5]{frac{a^frac{5}{4}}{a^-^frac{1}{4}}} = sqrt[5]{a^frac{3}{2}} =(a^frac{3}{2} )^frac{1}{5} =a^frac{3}{10}=sqrt[10]{a^3}$

г) $frac{3a}{a^2-9} -frac{3}{a^2-9} :(frac{a+2}{3a-3} -frac{1}{a-1} )= \frac{3a}{a^2-9} -frac{3}{a^2-9} :(frac{a+2}{3*(a-1)} -frac{1}{a-1})=frac{3a}{a^2-9} -frac{3}{a^2-9} : frac{a+2-3}{3*(a-1)} =\ frac{3a}{a^2-9}- frac{3a}{a^2-9}:frac{a-1}{3*(a-1)} = frac{3a}{a^2-9}- frac{3a}{a^2-9}:frac{1}{3} = frac{3a}{a^2-9}- frac{3a}{a^2-9} * 3 = \frac{3a}{a^2-9}- frac{9}{a^2-9} = frac{3a-9}{a^2-9} = frac{3*(a-3)}{(a-3)*(a+3)} =\ frac{3}{a+3}$