Question

Помогите плиз математика N355 N364

Answer 1

$frac{a}{ a^{2} -9ab} - frac{9b}{a^{2}-81b^{2}} = frac{a}{a(a-9b)} - frac{9b}{(a-9b)(a+9b)} = frac{a(a+9b)-9ab}{a(a-9b)(a+9b)} = \ = frac{a^{2}+9ab-9ab}{a(a-9b)(a+9b)} = frac{a^{2}}{a(a-9b)(a+9b)} = frac{a}{(a-9b)(a+9b)}$

$frac{x^{2}-25}{x^{2}-3x-10} = frac{(x-5)(x+5)}{(x-5)(x+2)} = frac{x+5}{x+2}$