1, the concept of fraction

The so-called fraction refers to A/B formula, where a and b are algebraic expressions, b contains letters, and b is not equal to 0. Where a is called the numerator of the fraction and b is called the denominator of the fraction. For example, x/y is a fraction, and x(y+2)/y is also a fraction.

2, the basic nature of the score

The numerator and denominator of a fraction are multiplied (or divided) by the same algebraic expression that is not 0 at the same time, and the value of the fraction remains unchanged. The formula is: A/B=(A*C)/(B*C), a/b = (a ÷ c)/(b ÷ c) (a, B and C are algebraic expressions, and B and C are not equal to 0).

3. Fractional multiplication and division algorithm

The multiplication rule of fractions: two fractions are multiplied, the product of molecular multiplication is the numerator of the product, and the product of denominator multiplication is the denominator of the product. Expressed in letters: a/b * c/d=ac/bd.

Law of division of fractions:

(1). Divide two fractions, invert the numerator and denominator of the divisor, and then multiply by the divisor. For example, a/b÷c/d=ad/bc.

(2) dividing by a fraction is equal to multiplying the reciprocal of this fraction: for example, A/B ÷ C/D = A/B * D/C.

4. Addition and subtraction algorithm of scores

Addition and subtraction of the same denominator fraction: addition and subtraction of the same denominator fraction and addition and subtraction of the same denominator numerator. Expressed in letters: A/CB/C = (AB)/C. Addition and subtraction of fractions with different denominators: the addition and subtraction of fractions with different denominators are divided into fractions with the same denominator, and then calculated according to the addition and subtraction rules of fractions with the same denominator. Expressed in letters: a/b c/d = (ad CB)/BD.

5. Equation with letter coefficient

6. Fractional equation

Equations with unknowns in the denominator are called fractional equations.

7.a=bc quantitative relation

8. Application of Fractional Equation