Bài 2:
a: ĐKXĐ: \(x\notin\left\{1;-1\right\}\)
b: \(P=\dfrac{2x^2+x^2-x-x^2-x}{\left(x-1\right)\left(x+1\right)}=\dfrac{2x^2-2x}{\left(x-1\right)\left(x+1\right)}=\dfrac{2x}{x+1}\)
c: Để P nguyên thì \(x+1\in\left\{1;-1;2;-2\right\}\)
hay \(x\in\left\{0;-2;-3\right\}\)