Bài 2:
`a, C=\frac{x}{2x-2}+\frac{x^2+1}{2(1-x^2)}` `(x ne ±1)`
`=\frac{x}{2(x-1)}-\frac{x^2+1}{2(x^2-1)}`
`=\frac{x(x+1)-x^2-1}{2(x-1)(x+1)}`
`=\frac{x^2+x-x^2-1}{2(x-1)(x+1)}`
`=\frac{x-1}{2(x-1)(x+1)}`
`=\frac{1}{2(x+1)}`
`b,` Thay `x=1/2(tm)` vào `C`
`⇒C=\frac{1}{2.(1/2+1)}`
`=\frac{1}{2.3/2}=1/3`
Vậy với `x=1/2` thì `C=1/3`
