2. The numerator and denominator of a fraction are polynomials, which are decomposed into factors respectively, and then the common factor is removed.
Two: general points. Step: First find out the simplest common denominator of all fractions, and then change the denominator of all fractions into the simplest common denominator. At the same time, each fraction enlarges its own molecule according to the multiple of the denominator.
The determination method of the simplest common denominator: the coefficient takes the product of the least common multiple of each factor coefficient, the highest power of the same letter and the power of a single letter.