Junior High School Mathematics Give Points!! Junior high school math urgent! Send points

Question 1. Results: 100 19

Process: Assuming that A runs the time t first, then B and C have a speed of 95 t and 90 t respectively, and then B takes 5 (95 t) to reach the end point, and the distance C runs forward during this time is 5 (95 t) (90 t) = 19 90, then C is 10-19 90 = 100 90 from the end point

Question 2. Result: Choose C

There are two kinds of profit margins, one is the cost profit margin (I feel that this question refers to this) and the other is the sales profit margin (according to this calculation, the result is 1 6, i.e., no answer).

Process: Set the cost to be x yuan, calculate the cost profit margin to get m =, the purchase price after the price increase is, the selling price is, the profit margin is, choose c

Question 1: Answer: 5 and 25 95 meters.

rt can see that D only ran 90 meters when B ran 95 meters, and it can be found that D's speed is 90 95 of B, and when B reaches the end of the line, B runs 5 meters, and it can be concluded that D ran 4 and 70 95 meters, and it can be concluded that C is 5 and 25 95 meters away from the end at this time.

Question 2: Answer: c.

If the profit of each piece before the price increase is m yuan, and the profit is 20%, then it can be concluded that the forward price of the price increase is m 4, and the purchase price should be increased by 25%, and the purchase price is m 4 125% = m 5, and the profit after the price increase is still m yuan, then the selling price after the price increase m 6 can be obtained, and the profit is 1 6 16%.

1) Set the speed of the armor to a

Time is 100 a

B's velocity is (100-50) 100 a=C's velocity is (100-10) 100 a=

B ran another 5 meters to the finish line, and it took 5 hours.

C ran the meter. At this point, the distance from the end point is 10-90 19 = 100 19 meters.

2) Commodity profit margin = (commodity selling price - purchase price) purchase price.

The purchase price of the commodity is m 20% = 5m yuan.

After the purchase price is increased, it is 5m (1+25%)=

The profit margin is m

So choose C

1. Very amazing topic, I have to admire the imagination of human beings now. Here we might as well understand the number 3, 1*3=3, 2*3=6, 3*3=9, 4*3=12,5*3=15,6*3=18,7*3=21,8*3=24,9*3=27 (all carry is less than 2, this should be noted) Shenzhou 5 Feitian * God = Feitian Shenzhou 5, God = 3, then fly = 9, no objection, I am speechless if I don't understand.

Boat < 3 is 0 or 1 or 2, it is known that Feitian Shenzhou 5 can be divisible by 3, then the sum of Fei + Tian + Shen + Zhou + 5 + can be divisible by 3, and the fourth position (the position starts from the beginning of the count, the same below) "five" * God = God does not consider the carry first, then "five" may be 1 or 4 or 7; The second position "fly" * god = five, it is reasonable not to consider that the carry of the five should be 7, according to reasoning, "five" can only be 7. And the No. 1 position "Heaven" * God = No., then there is a day is not equal to 0, "No. " is not equal to zero, considering that the No. 2 position cannot be carried, then the day is one of 1 and 2. The number is 3 or one of 6, and there is no doubt that the "number" can only be 6 and then the day is 2.

It seems that this is the answer to come out. Shenzhou 5 Feitian = 307692, Feitian Shenzhou 5 = 923076. （ps：

If you understand it yourself, you have to let others understand. ）

2. The work efficiency is increased by 25%, which is directly reflected in the construction period, then there is x 125% = x-20, (x is the construction period) x = 100 days.

3. A A (A means how many days A needs to do this project alone, the same is true for the following) B B cooperates for 2 days (condition 1), B B C C 4 days (condition 2), C C A day (condition 3), which means that A is very fast Condition to condition Condition to be B = 6, then a = 3. Pick B

1. 307692×3=9230762.The original plan takes x days.

x-1/(5/4x)=20

x=1003. b

Set A alone for x days, B y days, and C z days.

1/(1/x+1/y)=1/2

1/(1/y+1/z)=1/4

1/(1/x+1/z)=5/12

Solution x=3

.= uh... The most annoying thing is that it may be finished.,When you enter the answer and click "Submit",What pops up is that the problem has been solved and so much energy has been wasted.。。。

1. Fill in the blanks (no process required).

1.|x-4|+(y+2) =0, x=4, y=-2 2When|x²-4|+(x+2) = 0, x = 23

If x +1 3, then x 2 or x -2 4（2a-b）-(2a+b)=-2b

square + b square. 6.(-2a) (3a) = 6a to the 4th power.

7.(-2a) = -2a to the 6th power.

9.(3x+2)(3x-2)=9x squared-410(2x-3) (2x-3) = 4x squared - 911(x-2)²+8x＿=(x+2)²

12.(a+1)³/(a+1)=

of the squared. y(x+1)(x-1)

18.x 4-2x y +y 4 = unclear.

19.The coordinates of the intersection of the line y=2x and the line y=-x+3 are (1,2)20The opening direction of the parabola y=x is upward; The vertex coordinates are (0,0).

21.The opening direction of the parabola y=-3(x-4) -5 is downward; The vertex coordinates are (4,-5).

2. Solving the equation (process!!

4.(√x+2)+1=2

6.Find the difference between 1+2x+x and 2-x+2x.

3. Primary functions and parabolas (there must be a process!) ~~

1.Knowing the straight line y=-2x+2, find the area of the triangle enclosed by the line and the two coordinate axes.

2.It is known that the intercept of the line y=kx+b on the y-axis is 2, and the values of k and b are found by the point p(1,0).

3.Knowing that the point p(-1,m) is on the straight line y=-x+3, the value of m is obtained.

4.Find the intersection of the line y=x+2 and the line y=2x-1.

5.Find the intersection of the parabola y=(x-3) -1 with the axis.

6.Find the vertex coordinates of the parabola y=x -4x+3.

7.Find the domain of the function y=1 x+2.

8.Find the function y=1 |x|-1.

9.Knowing that the straight line y=2x+1, try to find its intercept on the x-axis.

10.Knowing that the line y=2x+b passes through the point p(1,-2), try to find its intercept on the x-axis.

11.Knowing that the straight line y=2x+1, try to find its intercept on the y-axis.

1. Fill in the blanks. ,y=0

Root number 2 or x < "Negative root number 2

7.-8a^6

8.-10a

14.(2x+5y)(2x-5y)

15.(x-1/2)^2

16.(2x+y-z)(2x-y+z)

18.(x^2-y^2)^2

20.Up (0,0).

21。Down (4, -5).

Hehe, make rolls.

The day before yesterday, I gave someone a review, a total of 14 questions.

As a result, I directly "copyed" and "pasted" my downstairs, and I was so distressed.

In the future, only single questions will be answered.

The last question from the left: y=2x+1

Let x=0 find y=1

So the intercept is 1

So many questions, 1000 points are about the same...

I can't do it myself, I'm lazy, I'm in the sixth grade, why is it so simple, or, you haven't studied the Olympiad?

Solution: The cost price of each product should be reduced by X yuan.

510-400）*m=【510*（1-4%）-400-x）】*m（1+10%）

x = A: The cost price of each piece of the product should be reduced by yuan.

The profit is: unit price profit per piece (510-400)m 110m sales volume increased by 10 pieces and the number of pieces is 110 m pieces.

If the profit is to remain unchanged, the unit price profit is the total profit of 110m 110 m 100 yuan.

4% reduction in sales price = 510 (1-4%) = yuan.

Solution: Let the cost price of each piece be reduced by X yuan.

510-400）*m=((510(1-4%)-400-x))*1+10%)*m

x = yuan) Answer: The cost price of the first piece of the product is reduced by yuan.

There are c7 combinations, 2 = 21 kinds, of which the same level has c22 + c32 + c22 = 5 probability of 5 21

Question 2 There are 2 situations: 1 level and 2 levels or 2 levels and 3 levels 1 and 2, that is, C31 multiplied by C21 = 6 types.

2 and 3 are c31 times c21 = 6 types.

The total combination has a72=21 and the probability is 2 7

1.The numerator is a2, take 2+a3, take 2+a2, take 2=1+3+1=5, denominator, a7, take 2=42, probability 5, 42

2.Since the requirement is an absolute value of 1

The numerator is a2, take 1*a3, take 1+a3, take 1*a2, take 1=6+6=12, the denominator is still a7, take 2=42, and the probability is 2 7

The principle is to take the intersection of the two, that is, the common part of the two solutions.

The answers are: 1, x 3, 2, empty set (or fill in no solution, the same meaning), 3, x -4, 4, -4 x 3, 5, empty set (or fill in no solution, the same meaning), 6, x -1

x＜2＜x＜1

3 to positive infinity. Empty setEmpty set.

Negative infinity to -1