pavelmager200638

(\frac{a}{c}+\frac{c}{a}-2)*\frac{1}{a-c}=\\\\\frac{a^2-2ac+c^2}{ac}*\frac{1}{a-c}=\\\\\frac{(a-c)^2*1}{ac(a-c)}=\\\\\frac{a-c}{ac}