(1) Multiply two numbers, the same sign is positive, the different sign is negative, and the absolute value is multiplied;

(2) Multiply any number by zero to get zero;

(3) Several factors are not zero, and the sign of the product is determined by the number of negative factors. Odd numbers are negative and even numbers are positive.

I believe that the students have mastered the knowledge points of the law of rational number multiplication in mathematics, and I hope that the students will succeed in the exam.

Definition of the power of seventh grade mathematics knowledge points

For the study of mathematical knowledge points, the following introduces the definition of power, hoping to help students learn well.

Definition of power:

The operation of (1) common factor product is called power;

(2) In power, the same factor is called base, the number of the same factor is called exponent, and the result of power is called power;

(3)a2 is an important non-negative number, that is, A2 ≥ 0; If a2+|b|=0? a=0，b = 0；

(4) According to the law, the decimal point of the cardinal number moves by one place and the decimal point of the square number moves by two places.

I believe that students can master the knowledge points of the definition of power in mathematics, and study hard!

The rational number addition rule of seventh grade mathematics knowledge points

The rational number multiplication rule of mathematics knowledge points in senior one II:

Multiply two numbers, the same sign is positive, the different sign is negative, and then multiply by the absolute value.

Any number multiplied by 0 is 0.

Two numbers whose product is 1 are reciprocal.

Multiply several numbers that are not 0. When the number of negative factors is even, the product is positive. When the number of negative factors is odd, the product is negative.

When two numbers are multiplied, the exchange factor and the product are in the same position.

ab=ba

Multiply three numbers, first multiply the first two numbers, or multiply the last two numbers first, and the products are equal.

C=a (BC)

Multiplying a number by the sum of two numbers is equivalent to multiplying this number by these two numbers respectively, and then adding the products.

a(b+c)=ab+ac

Writing specification for multiplication of numbers and letters;

(1) Numbers are multiplied by letters, and the multiplication sign should be omitted, otherwise it will be used.

(2) Numbers multiplied by letters. When the coefficient is 1 or-1, 1 should be omitted.

(3) The band score is multiplied by letters, and the band score becomes a false score.

If any rational number is represented by the letter X, the product of 2 and x is 2x, and the product of 3 and x is 3x, then the formula 2x+3x is the sum of 2x and 3x, 2x and 3x are the terms of this formula, and 2 and 3 are the coefficients of these two terms respectively.

Generally speaking, when combining formulas with the same letter factor, it is only necessary to combine their coefficients, and the obtained results are used as coefficients, and then multiplied by the letter factor, that is,

ax+bx=(a+b)x

In the above formula, X is the letter factor, and A and B are the coefficients of ax and bx respectively.

Support removal rules:

Parentheses are preceded by+. Remove brackets and the+sign before brackets. What is in brackets will not change the symbol.

Before parentheses is-,remove parentheses and-before parentheses, and change the sign of everything in parentheses.

The factors outside brackets are positive numbers, and the symbols of the items in the formula after removing brackets are the same as those of the corresponding items in the original brackets; The factor outside the bracket is negative, and the sign of each item in the formula after the bracket is opposite to that of the corresponding item in the original bracket.