Tìm a, b sao cho 

Câu hỏi: Tìm a, b sao cho $\frac{\text{1}}{\text{(x}+\text{1)(x}-\text{1)}}=\frac{\text{a}}{\text{x}+\text{1}}+\frac{\text{b}}{\text{x}-\text{1}}$

A. $a = \frac{-1}{2}; b = \frac{-1}{2}$

B. $a = \frac{1}{2}; b = \frac{1}{2}$

C. $a = \frac{1}{2}; b = \frac{-1}{2}$

D. $a = \frac{-1}{2}; b = \frac{1}{2}$