Question

упростите выражение ((a^2)/a^2-1)-a/a+1

Answer 1

$frac{a^2}{a^2-1}-frac{a}{a+1}=frac{a^2}{(a-1)(a+1)}-frac{a}{a+1} =$

$=frac{a^2}{(a-1)(a+1)}-frac{a(a-1)}{(a-1)(a+1)} =frac{a^2-a^2+1}{(a-1)(a+1)}==frac{1}{a^2-1}$