Ответ:
а)
\(\left(\frac{x}{y^2}-\frac1x\right):\left(\frac1y+\frac1x\right)=\frac{x^2-y^2}{xy^2}:\frac{x+y}{xy}=\frac{(x-y)(x+y)}{xy^2}\cdot\frac{xy}{x+y}=\frac{x-y}{y}.\)
б)
\(\left(\frac{a}{m^2}+\frac{a^2}{m^3}\right):\left(\frac{m^2}{a^2}+\frac ma\right)=\frac{a(m+a)}{m^3}:\frac{m(m+a)}{a^2}=\frac{a^3}{m^4}.\)
в)
\(\frac{ab+b^2}{3}:\frac{b^3}{3a}+\frac{a+b}{b}=\frac{b(a+b)}3\cdot\frac{3a}{b^3}+\frac{a+b}{b}=\frac{a(a+b)}{b^2}+\frac{b(a+b)}{b^2}=\frac{(a+b)^2}{b^2}.\)
г)
\(\frac{x-y}{x}-\frac{5y}{x^2}:\frac{x^2-xy}{5y}=\frac{x-y}{x}-\frac{25y^2}{x^3(x-y)}.\)
Приведём к общему знаменателю:
\(\frac{x^2(x-y)^2-25y^2}{x^3(x-y)}.\)
Ответ: а) \(\frac{x-y}{y}\); б) \(\frac{a^3}{m^4}\); в) \(\frac{(a+b)^2}{b^2}\); г) \(\frac{x^2(x-y)^2-25y^2}{x^3(x-y)}\).
