Rút gọn biểu thức
1)\(\frac{c\left(a+c\right)-a\left(a-c\right)}{\frac{c}{a-c}-\frac{a}{a+ c}}\)
2) \(\frac{\frac{x^2-y^2}{x}}{\frac{1}{x}-\frac{1}{y}}\)
3) \(x:\frac{x-1}{2}-\frac{\left(x-1\right)\left(x^2+4x+1\right)}{2x^2+2x}.\frac{-4x}{\left(x-1\right)^2}-\frac{4x^2}{x^2-1}\)