Who gave me 100 math problems for the first year of junior high school

Solution: (1) Let the total cost y (yuan) and the number of units sold x (sets), and obtain the functional relationship according to the title:

y=50000+200x．

2) If the software company needs to sell x sets of software to ensure that it does not lose money, there are:

700x≥50000+200x

Solution: x 100

A: Software companies need to sell at least 100 units of software to ensure that they don't lose money

1. "The difference between 2 times x and 3 is not greater than 8" The inequality listed is a) 2x 3 8 (b) 2x 3 8

c）2x－3＜8 （d）2x－3＞8

2. If x 3, then the following inequality holds a)x2 3x (b)x2 3x

c）x2＜－3x （d）x2≤－3x

3. The following statement is correct

a) x=2 is not a solution to inequality 3x>6.

b) x>2 is the set of solutions of inequality 3x>5.

c) x=2 is a solution to the inequality 3x>6.

d) All of the above statements are correct.

c） （d）

5. The positive integer solution of the inequality 3x+6 0 has

a) 1 (b) 2.

c) 3 (d).There are countless more.

6. If the solution of the equation about x is a non-negative number, then the condition that a satisfies is a) (b) (c) (d).

7. Let a b, then the set of solutions of the inequality group is

a) x b (b) x a (c) b x a (d) no solution.

8. The smallest integer solution of the group of inequalities is

a）0 （b）1 （c）2 （d）－1

9. If there is no solution to the inequality group, then the value range of m is a) m 11 (b) m 11

c）m≤11 （d）m≥11

10. The cost of a brand computer is 2400 yuan, and the price is 2980 yuan

a) 7% off (b) off (c) 8% off (d) off.

2. Fill in the blanks: (5 points per question, 25 points in total).

11.Expressed by inequality: a+3 is greater than 2 : 12If a13, the positive integer solution of inequality is

14 If there is no solution to the group of inequalities about x, then the range of values of a is 15 If a b c, then the set of solutions of the group of inequalities is 3. Calculation problem: Solve the following inequalities (groups) (10 points per question, 40 points in total)16. Solve the inequality: 7(x-1)< 4x+2 , and express its solution set on the number line.

17. Solving inequalities:

18. Solve the group of inequalities, and express the solution set on the number line.

19. Known 3 (2x+1) 2 (4x+1) + 7, simplification - 4. Answer questions: (45 points in total).

20. A software company has developed a book management software, and the initial investment in development and advertising costs is 50,000 yuan, and the software company needs to pay 200 yuan for installation and commissioning for each set of software sold. If each set is priced at 700 yuan, how many sets of software does the software company have to sell at least to ensure that it does not lose money? (10 points).

【Typical Example Questions】1

1.Equation. The number of solutions is ()a

Inside, make. The value range of the valid is ()a

Known functions. The image is about straight lines.

Symmetry, then. Probably ()a

Known to be an acute triangle, then ().

With the size can not be determined.

5.If the function.

The minimum positive period is.

And the maximum value is obtained at that time, then ()a

The range is ()a

d.Answer: Make separate functions in the same coordinate system.

The image has three intersections on the left, three intersections on the right, plus the origin, for a total of 2

c makes separate functions in the same coordinate system.

The image of the observation:

Just starting instantly,;

Instantaneously in the middle;

The final stage is.

time, 3The c-axis of symmetry passes through the highest or lowest point and can be equal to.

II.1It is known to be the first.

The angles of the second and third quadrants, then.

The value range is as follows:

2.Function. The domain is defined as.

then function. The domain is defined as.

3.Function. The monotonically increasing interval is 4Establish.

If function. In monotonically increasing increments, then.

The value range is as follows:

5.Function. The domain is defined as.

Answer: 1When the function is decrementing, 4Cause.

is a function. The interval with the largest range of increasing intervals about origin symmetry, i.e., 5

This question is very simple, first assume that the length of the car is x, then according to the question: it takes 20s to pass through a tunnel with a length of 300m.

So you can calculate the speed of the car.

Equal to (300+2x) 20

And then according to the question.

The time the lights shine on the train is 10s

It means. So there is:

300+2x

20*10=x

There is no solution to this equation.

Therefore, the length of the train cannot be found based on the above data.

Because ab=20, Xunxiao m is the midpoint of ab.

So read rotten am=bm=10

BC=10 is obtained from AC:BC=3:1

AD=20 is obtained from AD=AB, then DC=AD+AB+BC=50MD=AD+AM=30

1.The line segment BC is 10 cm long.

2.The line segment DC is 50 cm long.

3.The line segment MD is 30 cm long.

Solution: (1) Let the total cost y (yuan) and the number of units sold x (sets), and obtain the functional relationship according to the title:

y=50000+200x．

2) If the software company needs to sell x sets of soft and poor pure parts to ensure that it does not lose money, there are:

700x≥50000+200x

Solution: x 100

Answer: The software company must sell at least 100 sets of software in order for Liang Chang to ensure that he does not lose money