Question

1: R= $\frac{x}{x -y +z} + \frac{z}{x-y+z} + \frac{y}{y-x-z}$

Answer 1

los dos primeros son homogeneos
$\frac{x+z}{x-y+z} + \frac{y}{y-x-z}$
multiplicando los denominadores
$\frac{(x+z)(y-x-z)+y(x-y+z)}{(x-y+z)(y-x-z)}$
$\frac{xy-x^2-xz+yz-xz-z^2+xy-y^2+yz}{(x-y+z)(y-x-z)}$
$\frac{2xy+2yz-2xz-x^2-y^2-z^2}{(x-y+z)(y-x-z)}$