Question

2/(3+b^2)-12/(b^4-9)-2/(3-b^2)

Answer 1

$frac{2}{3+b^{2}}-frac{12}{b^{4}-9}-frac{2}{3-b^{2}}= frac{2b^{2}-6-12+2b^{2}+6}{b^{4}-9}=$
$=frac{4b^{2}-12}{b^{4}-9}=frac{4(b^{2}-3)}{b^{4}-9}=frac{4(b^{2}-3)}{(b^{2}-3)(b^{2}+3)}=$ $frac{4}{b^{2}+3}$