1, the key of general division is to determine the simplest common denominator of several fractions, and its steps are as follows: ① List the divisors of each denominator respectively;

② Multiply the denominator, and if there is a common divisor, the result is the least common multiple of the denominator;

(3) All the letters that appear or the factors based on letters should be taken;

(4) The factor with the same letter or the power of the factor with letters takes the maximum exponent;

⑤ Multiply all the above formulas to get the simplest common denominator;

2. Steps of general division: ① First, find the simplest common denominator of the denominator of the original score;

(2) According to the basic properties of fractions, the original fractions are converted into fractions with the simplest common denominator as the denominator.