$\dfrac{x}{x+1}$ `-`$\dfrac{2x-3}{1-x}$ `-`$\dfrac{3x^2+5}{x^2-1}$ (ĐKXĐ:`x`$\neq$ `±1`)
`=` $\dfrac{x}{x+1}$ `+`$\dfrac{2x-3}{x-1}$ `-`$\dfrac{3x^2+5}{(x-1)(x+1)}$
`=`$\dfrac{x(x-1)+(2x-3)(x+1)-(3x^2+5)}{(x-1)(x+1)}$
`=`$\dfrac{x^2-x+2x^2-x-3-3x^2-5}{y}$
`=`$\dfrac{-2x-8}{(x-1)(x+1)}$
`=`$\dfrac{-2x-8}{x^2-1}$