Question

. Выполните сложение и вычитание дробей.​

Answer 1

ответ:

$\displaystyle 1)\frac{1}{3a}\\ \\2)-\frac{4y+15}{y^2-25}$

решение:

$\displaystyle 1)\frac{1}{2a}-\frac{1}{6a}=\frac{2}{6a}=\frac{1}{3a} \\\\2)\frac{3}{5-y}-\frac{y}{y^2-25}=\frac{3}{-(y-5)}-\frac{y}{y^2-25}=\frac{3}{-(y-5)}-\frac{y}{(y-5)(y+5)}=\\\\-\frac{3}{y-5}-\frac{y}{(y-5)(y+5)}=-\frac{3(y+5)+y}{(y-5)(y+5)}=-\frac{3y+15+y}{(y-5)(y+5)}=-\frac{3y+15+y}{y^2-25}=\\-\frac{4y+15}{y^2-25}=$