Question

дам 30 балов решите с объяснением ​

Answer 1

Ответ:

$\displaystyle \frac{y-x}{y+x}\cdot \Big(\frac{x+3y}{x-y}-\frac{y}{x}\Big)=\frac{-(x-y)}{y+x}\cdot \frac{(x+3y)\cdot x-y\cdot (x-y)}{x\cdot (x-y)}=\\\\\\=-\frac{1}{x+y}\cdot \frac{x^2+3xy-xy+y^2}{x}=-\frac{x^2+2xy+y^2}{(x+y)\cdot x}=\\\\\\=-\frac{(x+y)^2}{(x+y)\cdot x}=-\frac{x+y}{x}$