Question

помогите решить эти примеры !

Answer 1

Упростить

$\frac{12-x}{x^2+6x}+\frac{3}{x^2-6x}-\frac{6}{x^2-36}=\\\frac{12-x}{x(x+6)}+\frac{3}{x(x-6)}-\frac{6}{(x-6)(x+6)}=\\\frac{(12-x)(x-6)+3(x+6)-6x}{x(x-6)(x+6)}=\\ \frac{12x-72-x^2+6x+3x+18-6x}{x(x-6)(x+6)}=\\\frac{-x^2+15x+54}{x(x-6)(x+6)}=\\ \frac{-(x+3)(x-18)}{x(x-6)(x+6)}$

2)

$\frac{2(x+5)-4(x-5)-x^2-15}{(x-5)(x+5)}=\\ \frac{-x^2-2x-15}{(x-5)(x+5)}=\frac{-(x+5)(x+3)}{(x-5)(x+5)}=-\frac{x+3}{x+5}$

3)

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