Question

frac{1}{a-b} - frac{1}{b-a} - frac{2a}{a^2-b^2}

Answer 1

$frac{1}{a-b} - frac{1}{b-a} - frac{2a}{a^2-b^2}=frac{1}{a-b} + frac{1}{a-b} - frac{2a}{a^2-b^2}=frac{2}{a-b} - frac{2a}{a^2-b^2}=$

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