Представьте в виде дроби: a) $$\frac{y-20}{4y} + \frac{5y-2}{y^2}$$ b) $$\frac{1}{5c-d} - \frac{1}{5c+d}$$

a) $$\frac{y-20}{4y} + \frac{5y-2}{y^2} = \frac{y(y-20)}{4y^2} + \frac{4(5y-2)}{4y^2} = \frac{y^2-20y+20y-8}{4y^2} = \frac{y^2-8}{4y^2}$$ б) $$\frac{1}{5c-d} - \frac{1}{5c+d} = \frac{5c+d}{(5c-d)(5c+d)} - \frac{5c-d}{(5c-d)(5c+d)} = \frac{5c+d - (5c-d)}{(5c)^2 - d^2} = \frac{5c+d - 5c+d}{25c^2 - d^2} = \frac{2d}{25c^2 - d^2}$$