1、3/7? - 4/3

2、8/9 + 1/27

3、5/6 – 2/9 ×3

4、5/4 + 1/4

5、6÷ 3/8 – 3/8

Induction of mathematical knowledge points of "addition and subtraction of fractions";

Although 1, general fraction and reduced fraction are all aimed at fractions, they are two opposite variants. Reduction is for one score, while general scores are for multiple scores; Simplification is to simplify fractions, and general fractions are to simplify fractions, thus unifying the denominator of each fraction.

2. Both general score and approximate score are deformed according to the basic properties of the score, and their similarity is to keep the value of the score unchanged.

3. The general denominator is written in the form of unexpanded continuous product, and the numerator multiplication is written in polynomial to prepare for further operation.

4. The basis of general score: the basic nature of score.

5. The key to general scores: determine the common denominator of several scores. Usually, the product of the highest power of all factors of each denominator is taken as the common denominator, and such common denominator is called the simplest common denominator.