[tex]\frac{1}{(x-1)(x+1)}[/tex] × [tex]\frac{2+x-1}{2}[/tex] : [tex]\frac{x+1-2}{2}[/tex] =
= [tex]\frac{1}{(x+1)(x-1)}[/tex] × [tex]\frac{x+1}{2}[/tex] × [tex]\frac{2}{x-1}[/tex]
= [tex]\frac{1}{(x-1)^{2} }[/tex]
