Mixed calculation questions of rational numbers in junior high school mathematics Beijing Normal Un

——— the above calculation questions, I am looking for death, and some of them are written by myself) 1 Calculation questions: (10 5=50 )

2.Calculation problem: (10 5 = 50).

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1.Fill-in-the-blank questions:

1) If yes, then ac 0;If , then ac 0;

2) If , then abc= ; a2b2c2= ;

3) Knowing that a, b are inverse numbers to each other, c and d are reciprocal to each other, and the absolute value of x is equal to 2, then x2-(a+b)+cdx= .

2 Calculation: Practical application in life].

A buys a lot of ** for 1,000 yuan, and then he resells this lot of ** to B for a profit of 10%, and then B resells this lot of ** to A, but B loses 10%.In the end, A sold this lot of ** to B at a 10% discount of the ** sold by B to A, and in the above ** transaction ( ).

a A is just breakeven; b A profit of 1 yuan;

C A makes a profit of 9 yuan; d A loses money.

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1.(1)>，2)24，-576;(3) 2 or 6[hint: =2 x2=4,x= 2]. 2.(1)-31; (2)-8 (3)224

Practical application in life] b

— the above exercises).

I've got it for you, can I see if it's okay? I did my best.

Rational math is the first lesson of mathematics just entering junior high school, so students must lay a good foundation and learn the first lesson of the school year.

Mixed operation of rational numbers in junior high school (1) (9)-(13)+(20)+(2).

Answers to rational number calculation questions

Definition of Rational Numbers in Mathematics Rational numbers can be divided into integers and fractions. Any rational number can be written as the fraction m n (m, n are both integers, and n ≠0). Any rational number can be represented on a number line.

These include integers and fractions commonly referred to by the Pulsor Wisdom, which can also be expressed as finite decimals or infinitely cyclic decimals.

This definition applies to both decimal and other carry systems of numbers, such as binary. Mathematically, a rational number is a ratio of an integer a to a non-zero integer b, usually written as a b, so it is also called a fraction. The Greek word "originally meant "rational number", but the Chinese translation was inappropriate and gradually became "reasonable number".

Infinite non-cyclic decimal numbers are called irrational numbers (e.g., pi), and rational numbers and irrational numbers are collectively called real numbers. The set of all rational numbers is denoted as qThe following basic answers are all rational numbers:

1) Integers include: positive integers, 0s, and negative integers are collectively referred to as integers.

2) Fractions include: positive scores and negative scores are collectively referred to as fractions.

3) Decimals include: finite decimals, infinite cyclic decimals. And fractions are also collectively referred to as decimals, because the fractions are mutualized.

Rational Numbers Chapter - The Opposite Number Combination Method is the sum of two numbers that are opposite to each other is 0, and when we calculate, we can combine the two numbers that are opposite to each other to calculate first.

In the addition and subtraction of rational numbers, the combination of the same sign method introduces the addition and subtraction of negative numbers more than the primary school, and some students will confuse the minus sign with the negative sign when calculating, and do not know how to calculate, so we can combine the same sign when calculating, and finally calculate according to the addition and subtraction rule of rational numbers.

( 3) 4 ( 3) 1 ( 4) Analysis: First simplify the calculation formula, you can get: (3) 4+3 1 (4), you can find that -3 and 3, -4 and 4 in the problem are opposite to each other, you can add the two numbers of these two groups of opposite numbers, and the sum is 0

Solution: Original 3 4 3 1 4 ( 3 3) (4 4) 1 1

Further information: Rational numbers are a collective term for integers (positive integers, 0s, negative integers) and fractions, which are a collection of integers and fractions.

An integer can also be thought of as a fraction with a denominator of one. Real numbers that are not rational numbers are called irrational numbers, i.e., the fractional part of an irrational number is an infinite number that is not cyclical. It is one of the important contents in the field of "number and algebra", which has a wide range of applications in real life, and is the basis for continuing to learn real numbers, algebraic formulas, equations, inequalities, Cartesian coordinate systems, functions, statistics and other mathematical content and related subject knowledge.

The set of rational numbers can be represented by the uppercase black orthography symbol q. But q does not denote a rational number, and a set of rational numbers and a rational number are two different concepts. A rational number set is a set of elements that are all rational numbers, while a rational number is a set of all the elements in a rational number set.

Technique 1: The sum of two numbers that are opposite to each other is 0, and we can combine the two numbers that are opposite to each other to calculate when calculating.

Example 1: ( 3) 4 ( 3) 1 ( 4) Analysis: First simplify the calculation formula, and you can get:

3) 4+3 1 ( 4), you can find that -3 and 3 and -4 and 4 in the problem are opposite numbers to each other, and you can add these two sets of opposite numbers to sum up to 0Solution: Original 3 4 3 1 4 ( 3 3) (4 4) 1 1

Technique 2: The combination of the same sign in the addition and subtraction of rational numbers, than the primary school introduces the addition and subtraction of negative numbers, some students will confuse the minus sign with the negative sign when calculating, and do not know how to calculate, so we can combine the same sign when calculating, and finally calculate according to the addition and subtraction rules of rational numbers.

Example 2: ( 8) (10) (3) (9) 2 Analysis: Simplify the calculation formula first, and you can get:

8+10+( 3) (9) 2, then when calculating, we can add all the positive numbers first, put all the negative numbers together and add them first, and then calculate according to the law. Solution: Original 8 10 3 9 2 (8 10 2) (3 9) 20 12 8

Primitive = (-2 3) + (1 4) - (1 6) - (1 2) primitive = -8 - (7 2) + 2 - (1 2) + 12 primitive =

Original = (-2 3)+

Original = (-3 and 2 3) + and 2 3) +

8.Original = [31 2-(5 4 7 5+7 2)] 9 8).

Tip: Fill in the median of nine digits in the nine-square** position.

Put the largest number in the middle of the first row.

Put the smallest number in the middle of the third row.

Place the second largest number in the bottom left corner.

Put the second smallest number in the top right corner.

In this way, you can basically set the shape. The rest of the spaces should be filled in as the sum of the three numbers of one of any two lines.