Summary of rational number mind map in seventh grade mathematics
Introduction to rational number words in seventh grade mathematics.
Chinese name: rational number
English: rational numbers
Symbol: q
Integers and fractions. Positive integers and fractions are collectively referred to as positive rational numbers, and negative integers and fractions are collectively referred to as negative rational numbers. Therefore, the number of rational number sets can be divided into positive rational number, negative rational number and zero number. Since any integer or fraction can be converted into a cyclic decimal, and vice versa, every cyclic decimal can also be converted into an integer or fraction, so a rational number can also be defined as a cyclic decimal. The set of rational numbers is an extension of the set of integers. In the set of rational numbers, the four operations of addition, subtraction, multiplication and division (divisor is not zero) are unimpeded. Order of rational numbers: If a-b is a positive rational number, it is said that A is greater than B or B is less than A, and it is recorded as a>b or B.
Rational number arithmetic in seventh grade mathematics
1. Add the same sign, take the same sign, and add the absolute value.
2. Add symbols with different absolute values, take the addend symbol with larger absolute value, and subtract the one with smaller absolute value from the one with larger absolute value. Two opposite numbers add up to 0.
When a number is added with 0, it still gets this number.
4. The result of adding antonyms must be 0.
pay attention to
One is to determine the symbol of the result; The second is to find the absolute value of the result. When rational numbers are added, it is first judged whether the symbols of two addends are the same sign or different sign, and whether there is 0, so as to determine which rule to use. In the process of application, we must bear in mind that "there is a symbol first, then there is an absolute value", so that we will not make mistakes if we are skilled. The addition of multiple rational numbers can be calculated from left to right, or the addition algorithm can be used, but before writing, you must think clearly which one should be calculated from left to right.
subtraction
rule
Rule of rational number subtraction: subtracting a number is equal to adding the reciprocal of this number. Among them: two changes: subtraction becomes addition, and subtraction becomes its opposite number to do addend. Invariant: The minuend is invariant. It can be expressed as: a-b=a+(-b).
increase
rule
(1) Multiply two numbers, the same sign is positive, the different sign is negative, and the absolute value is multiplied. For example: (-5)? (-3)= 15 (-6)? 4=-24 。
(2) Any number multiplied by 0 will get 0. For example: 0? 1=0
(3) Multiply several numbers that are not equal to 0, and the sign of the product is determined by the number of negative factors. When the negative factor is odd, the product is negative; When the negative factor is a non-zero even number, the product is positive. And multiply their absolute values. For example: (-10)? 〔-5〕? (-0. 1)? (-6)= The product is a positive number, and (-4)? (-7)? (-25)= The product is negative.
(4) Multiply several numbers. When a factor is 0, the product is 0. Example: 3? (-2)? 0=0 。
(5) Two rational numbers whose product is 1 are reciprocal. (The product of 1 is negative reciprocal) For example,? 3 and? 1/3,? 3/8 and? 8/3。
separate
rule
(1) divided by a number is equal to multiplying the reciprocal of this number. (Note: 0 has no reciprocal)
(2) Divide two numbers, the same sign is positive and the different sign is negative, and divide by the absolute value.
(3)0 divided by any number that is not equal to 0 is equal to 0.
note:
0 cannot be divided under any circumstances.
Seventh grade mathematical rational number mind map related articles;
1. Handwritten newspaper with pictures of mathematical rational numbers.
2. The first volume of the first day of mathematics mind map
3. The seventh grade mathematical rational number handwritten newspaper Volume I.
4. The seventh grade mathematical mind map
5. How to draw a map for your mind?
6. Math Mind Map of Grade One.