Помогите 854 а,б Очень надо))

[latex] \frac{1-a^2}{a^3+2a^2+a} = \frac{(1-a)(1+a)}{a(a^2+2a+1)} = \frac{(1-a)(1+a)}{a(a+1)(a+1)} = \frac{1-a}{a(a+1)} [/latex] [latex] \frac{x^2+xy+y^2}{x^6-x^3y^3} = \frac{x^2+xy+y^2}{(x^2-xy)(x^4+x^3y+x^2y^2)} = \frac{x^2+xy+y^2}{(x^2-xy)x^2(x^2+xy+y^2)}=\\= \frac{1}{x^2(x^2-xy)} [/latex]