Quy đồng mẫu thức của các phân thức x − 2 3(x − 1) , 5 2(x + 1) , x + 3 x 2 − 1  ta được:

A.  x − 2 3(x − 1) = 2(x − 2)(x + 1) 6(x 2 − 1) , 5 2(x + 1) = 5(x + 1) 6(x 2 − 1) , x + 3 x 2 − 1 = 2(x + 3) 6(x 2 − 1)

B.  x − 2 3(x − 1) = 2(x − 2) 6(x 2 − 1) , 5 2(x + 1) = 15(x − 1) 6(x 2 − 1) , x + 3 x 2 − 1 = 6(x + 3) 6(x 2 − 1)

C.  x − 2 3(x − 1) = 2(x − 2)(x + 1) 6(x 2 − 1) , 5 2(x + 1) = 15(x − 1) 6(x 2 − 1) , x + 3 x 2 − 1 = 6 6(x 2 − 1)

D.  x − 2 3(x − 1) = 2(x − 2)(x + 1) 6(x 2 − 1) , 5 2(x + 1) = 15(x − 1) 6(x 2 − 1) , x + 3 x 2 − 1 = 6(x + 3) 6(x 2 − 1)