Help! Do four questions. Tonight, you have to help

You're an elementary school student, right? China's education is really a failure, and now the question of not being able to do so has been asked...

1.18 24 = 432 (tons).

2.Solution: There are x copies of this batch of readings.

x-250=3/5x+20%x

x-3/5x-20%x=250

x=1250

3.From the inscription, it can be seen that the volume of the two eggs is the volume of the water surface changed, because the question says that the water's edge changes and the mouth of the cup.

Flat, that is to say, the volume of the change is added to the previous volume of the whole cup 1 3 then only the volume of the change is required to be two.

The volume of two eggs can be used to find the volume of the entire cup, and the specific solution is as follows:

5x5 x8x3=600 cubic centimeters.

4.Are they two questions? When b is 40% and 25% respectively? Then your question is wrong, it should be the sixth grade of school.

The total number of people, right? I can only solve it according to my understanding.

1) When b is 40%, the total number of sixth graders is x

40%x+84=x x=140

2) When B is 25%, the total number of sixth graders is X

25%x+84=x x=

Obviously not, then I understand that you mean that the number of sixth graders is 25% of the whole school.

Like? That's how it should be: still set the number of sixth graders at x

40%x+84=x

x=140140 25%=560 (person).

Therefore, there should be 560 students in the whole school.

You're too sloppy.,The questions haven't been copied well.,There's no picture yet.,Only this once.,Don't ask again next time.,Do it yourself.,Even if you don't know how the teacher won't say yours.,And my numbers are calculated by mouth.,You take a look at it yourself.,How to solve each question to figure it out.。 Good luck with your studies!

(1) From the figure of question 27-3, it can be seen that the image of y2 passes through the points (0, 60) and (60, 90), and the solution: substituting x=0, y=60, x=60y=90 into y=tx+b, gets:

60=0t+b, solution {b=60

90=60t+b, get: {t=1 2

The functional relationship between y2 and t in the figure 27-3 is y2=(1 2)t+60

2) the coordinates of point a (120 11, 720 11), point a is the intersection of y=6t(0t 30) and y2=(1 2)t+60;

The coordinates of point b (600 13, 1080 13), point b is the intersection of y=-6t+360(30 t 60) and y2=(1 2t)+60.

3) PS: Actually, I think the practical significance of the second question is that when the minute hand turns how much it coincides with the clock, it is more practical.

4、limf(x)=2+b

x→1+limf(x)=a+1

x→1-limf(x)=1-a

x Tease -1+

limf(x)=b

x Chatan Commissariat 1-

Then 2+b=a+1....1)

1-a=b...2)

Solution (1), (2), get.

a=1 ，b=0

Solution: x=a+1 a, then x =a+1 a+2, so that is, the rubber closed width proof (x -2)- 2>=x-2 i.e., proof (x -2)+2>=x+ 2, i.e., proof [ (x liangliang-2)+2] >x+ 2) i.e., proof state orange (x -2)+4 (x -2)+4>=x +2 2x+2 i.e., proof 4 (x -2)>=2 2x i.e.

The coordinates of the intersection of the function y=x+4 and y=-2x-1 are the solution of the equation (x+4=-2x-1), and the coordinates of the intersection are (-5 3, 7 3).

If the coordinates of the intersection of the primary function y=kx+b and the x-axis are (-2,0), then the solution of the equation kx+b=0 is (-2).

The math tutoring team will answer for you, if you don't understand, please ask.

1. The abscissa is the solution of x+4=-2x-1, and the intersection coordinate is (-5 3, 7 5).

2. Substituting (-2,0) into y=kx+b to get 0=-2k+b, that is, b k=2.

So the solution of kx+b=0 is x=-b k=-2.

The beginning of the day is far away, and the middle of the day is near.