a: ĐKXĐ: x<>0; x<>1; x<>-1
b: \(P=\left(\dfrac{x+1}{2\left(x-1\right)}-\dfrac{2x}{\left(x-1\right)\left(x+1\right)}\right)\cdot\dfrac{2x}{x-1}\)
\(=\dfrac{x^2+2x+1-4x}{2\left(x-1\right)\left(x+1\right)}\cdot\dfrac{2x}{x-1}\)
\(=\dfrac{\left(x-1\right)^2}{\left(x-1\right)\left(x+1\right)}\cdot\dfrac{x}{x-1}=\dfrac{x}{x+1}\)
c: Khi P=2 thì 2x+2=x
=>x=-2