Question

помогите пожалуйста!!!!!!

Answer 1

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

.
$frac{8}{ a^{2}-16} - frac{4}{ a^{2} -4a} = frac{8}{(a-4)(a+4)}- frac{a}{a(a-4)}= frac{8a-a(a+4)}{a(a-4)(a+4)}= \ \ frac{8a-a^{2}-4a}{a(a-4)(a+4)} = frac{4a-a^{2} }{a(a-4)(a+4)} = frac{a(4-a)}{-a(4-a)(a+4)}=- frac{1}{a+4}$