номер 150

а) \[ \left(\frac{x}{y^2}-\frac1x\right):\left(\frac1y+\frac1x\right) =\frac{x-y}{y}. \]

б) \[ \left(\frac a{m^2}+\frac{a^2}{m^3}\right):\left(\frac{m^2}{a^2}+\frac ma\right) =\frac{a^3}{m^4}. \]

в) \[ \frac{ab+b^2}{3}:\frac{b^3}{3a}+\frac{a+b}{b} =\frac{a(a+b)}{b^2}+\frac{a+b}{b} =\frac{(a+b)^2}{b^2}. \]

г) \[ \frac{x-y}{x}-\frac{5y}{x^2}\cdot\frac{x^2-xy}{5y} =\frac{x-y}{x}-\frac{x-y}{x}=0. \]