Quy đồng mẫu thức của các phân thức

Câu hỏi: Quy đồng mẫu thức của các phân thức $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}$  ta được:

A. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{5(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{2(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

B. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

C. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

D. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$