Question

Помогите пожалуйста № 880

Answer 1

$frac{a-b}{a^3-b^3} = frac{a-b}{(a-b)(a^2+ab+b^2)} = frac{1}{a^2+ab+b^2} \ \ frac{p^3+q^3}{2p+2q} = frac{(p+q) (p^2-pq+q^2)}{2(p+q)} = frac{p^2-pq+q^2}{2} \ \ frac{x^3-y^3}{x^2-y^2} = frac{x^2+xy+y^2}{x+y} \ \ frac{a^2+2ab+b^2}{a^3+b^3} = frac{(a+b)^2}{(a+b)(a^2-ab+b^2)} = frac{a+b}{a^2-ab+b^2} \ \ frac{m^2+n^3}{2(m^2-mn+n^2)} = frac{m+n}{2} \ \ frac{a^2-az}{a^3-z^3} = frac{a(a-z)}{(a-z)(a^2+az+z^2)} = frac{a}{a^2+az+z^2}$