(а/(a-b)-(a+b)/a)*(a+b)/a (b/(a-b)-b/(a+b))*(a-b)/b (a/c+c/a-2)*1/(a-c)              

1. [latex](\frac{a}{a-b}-\frac{a+b}{a})*\frac{a+b}{a} = \frac{a^2-a^2+b^2}{a(a-b)}*\frac{a+b}{a}=\frac{b^2(a+b)}{a^2(a-b)}[/latex] 2. [latex](\frac{b}{a-b}-\frac{b}{a+b})*\frac{a-b}{b}=\frac{ab+b^2-ab+b^2}{a^2-b^2}*\frac{a-b}{b}=\frac{2b^2(a-b)}{(a-b)(a+b)b}=\frac{2b}{a+b}[/latex] 3. [latex](\frac{a}{c}+\frac{c}{a}-2)*\frac{1}{a-c}=\frac{a^2+c^2-2ac}{ac}*\frac{1}{a-c}=\frac{(a-c)^2}{ac(a-c)}=\frac{a-c}{ac}[/latex]