Question

a+b/a^2-4b+4a-b^2*16-b^2-a^2-2ab/a^2+ab

Answer 1

$frac{a+b}{a^2-4b +4a - b^2} * frac{16-b^2-a^2-2ab}{a^2+ab} = \ \ = frac{a+b}{(a-b)(a+b) + 4(a-b)} * frac{16- (b^2+a^2+2ab) }{a(a+b)}= \ \ = frac{a+b}{(a-b)(a+b+4) } * frac{16- (a+b)^2}{a(a+b) } = \ \ = frac{(4-(a+b))(4+a+b)}{a(a-b)(a+b+4)} = frac{4-(a+b)}{a(a-b)}$