Help me with a few math problems! Please help me do another math problem!

3.First of all, remove the brackets, the root number 28 multiplied by the root number 7 is 14, the root number 7 times the root number 7 is 7, the 2 root number 3 times the root number 7 is 2 root number 21, and the root number 84 can be turned into 2 root number 21, pay attention to the plus and minus signs, so the result is 21

1: Because 3 13 4 so the integer part of 13 is 3, i.e. m=3 n= 13-3 m-n=3-( 13-3)=6- 13 2: Because the 3rd root number 3x-7 and the 3rd root number 3y+4 are opposite numbers to each other So (3x-7)+(3y+4)=0 then x+y=1 Because m-2 and (1-m+n) are opposite numbers to each other so (m-2)+ 1-m+n)=0 So m-2=0,1-m+n=0 is m=2,n=1 x+m+m+n=(x+y)+m+n=1+2+1=4 then the square root of x+m+y+n = the square root of 4 = the square root of 2 x+m+y+n = the square root of 4 3:

Remember.

Set the original car x cars, and the original number of days has y

Days (x-6) (y+3) = (x+4) (y-1) (status of late completion of tasks and status of early completion of tasks).

x-6)y=x*y-3(x-6) (the amount of work completed in the previous y days is the total amount of work minus three days' work in the case of a late completion task).

Solution: x=16y=5

Solution |3x-1|≤2

3x-1|=2 or |3x-1|＜2

If 3x-1 2, then |3x-1|The solution set of =2 is x=1 if 3x-1 2 and x=1 3

x=1 or x=1 3.

A completes 1 12 per day, and B completes 1 15 per day

So there is 9 10 divided by (1 12 + 1 15) = 6 days.

So it will take 6 days to complete.

Let the quantity of work be 1, then the efficiency of A and B is 1 10, 1 15 respectively, and now the number of days that B works first is days, and the remaining days are days.

A's work efficiency is 1 12 B's work efficiency is 1 15, the first 1 10 is completed by B alone, and the remaining 9 10 takes 9 10 (1 12 + 1 15) = 6

A and B 1 day are 1 12 and 1 15 respectively

A: It will take another 6 days.

1 represents a point where the distance from the number line to -5, 2 is equal to 7. Therefore, there are: -5, -4, -3, -2, -1, 0, 1, 2

Suppose the car drops off the student at a distance of x kilometers from the starting point for him or her to walk, turns back to pick up the other student, and then arrives at the destination at the same time.

Car: Walking = 45:5 = 9:1

Total distance walked: 30-x+x 9=30-8x 9Total distance by car: 30+(9-1)x 9*9 (9+1)*2=30+8x 5

So: (30 + 8 x 5) :(30-8 x 9) = 9: 1x = 25 km.

30-8x 9) 5=14 9 hours.

8 + 14 9 = 9 points 100 3 points.

Students from both classes can arrive at 9:100 a.m. at the earliest.

First class A took the bus, class B walked, and the two classes departed at the same time.

The speed of the vehicle is 45km h, 30km in two places, because t=s v so t=2 3 h

After the car arrives at the destination, Class A also arrives, and the car returns immediately. At this time, class B also walked 2 3 h and walked 10 3 km

Now the distance between the car and the B bus is 80 3 km, the time for the car and the B bus to meet is 8 15 h, after the B bus, the car is returning, and the return is only 8 15 h

So the time it takes in the end is 2 3 + 8 15 + 8 15 = 26 15 h = 104 minutes.

So arrived at 9:44.

Set up to walk to the meeting of people and vehicles for x hours.

Then 5x+45x=30*2 gives x=hour, hour, hour, walking, and 6km

24 45 = 8 15 hours.

And then that's 26 and 15 hours, which is 112 minutes, and it starts at 8 o'clock, which is 9:52.

When Naughty was doing a subtraction problem, he looked at the 2 on the subtracted tens of digits as a 5, and the result was a difference of 18. What should be the correct difference?

1.50 for 1 hour for masters, 25 for 1 hour for apprentices, 300 (50+25) = 4 hours.

2.300 (80-65)= 20 minutes!

The premise here is that the distance from the library to the school must be greater than 1600 meters, haha).

Question 1, 4 hours; Question 2, 20 minutes.

Process: The master can 50 in 1 hour, and the apprentice can 25 in an hour, so 75 an hour together, so the total time = 300 75 = 4 hours.

2. If the time is t, then 65t+300=80t, and t=20 minutes.

1. From the title, the master has 50 in 1 hour, 25 apprentices in 1 hour, and the master and apprentice have completed a total of 75 per hour, and the task can be completed in x hours, 75x=300 x=4

2. From the title, it is said that the small journey of 300 meters + the distance of the small continuation = the distance of the small Asian line, because the distance of the small continuation is equal to the time, therefore, if you can catch up with the small after y minutes, there are 300 + 65y = 80y and y = 20

4. 100 million square kilometers = 149 million square kilometers, 3600 14900x100% =

5. The output value of factory B is 4200 + 360 = 45.6 million yuan, 4560 4200x100% =

Baby, you have to work hard. Otherwise, the end of the semester will be difficult.