The length of an express train is 168cm, and that of a local train is 184cm. The two trains run in opposite directions. It takes 4 seconds from meeting to leaving, and it takes 16 seconds from catching up with the local train to leaving Find the speed of two cars

The length of an express train is 168cm, and that of a local train is 184cm. The two trains run in opposite directions. It takes 4 seconds from meeting to leaving, and it takes 16 seconds from catching up with the local train to leaving Find the speed of two cars

Let the speed of fast train be xcm / s and that of slow train be YCM / s
There are equations
4（x+y)=168+184
16(x-y)=168+184
The solution is as follows
x=46.75
y=41.25

What is the polar equation of x-root 3Y = 0?

x-√3y=0
y=√3/3x
a=π/6

2. A truck team finished transporting a batch of cement in three days. On the first day, it transported 5 / 14 of the cement. On the second day, it transported 40 tons more than on the first day. On the third day, it transported this batch of water
1. Read a book, the first day read 1 / 8 of the book, the second day than the first day more than 12 pages, the third day than the second day more than 6 pages, just read half of the book, the book has several pages
3. A car from a to B has traveled 42 kilometers in the first hour and 1 / 5 of the whole journey in the second hour. The rest of the journey is 6 kilometers less than 2 times of the journey already traveled. How many kilometers are there between a and B?
4. A scientific research group all participate in part-time study, and 5 / 2 of the group take part in computer. The remaining 1 / 3 are more than 3 people take part in mechanical class. There should be 15 people take part in University further study. How many people are there in this scientific research group?
5. A and B run from East and west at the same time. Car a runs 38 kilometers per hour, while car B runs 52 kilometers per hour. The two cars meet at 36 kilometers from the midpoint. How many kilometers is the distance between East and West?
6. A train from city a to city B runs 60 kilometers in the first hour, which is 1 / 6 less than the second hour. It runs 1 / 8 of the whole journey in two hours. If it runs at the average speed of the previous two hours, how many hours will it take to reach city B?
T.T
It's better to use formula instead of equation. If you use equation, please solve it step by step
If you use almost all the formulas, you can add a fortune reward

A train from city a to city B runs 60 kilometers in the first hour, which is 1 / 6 less than that in the second hour. It just runs 1 / 8 of the whole journey in two hours. If it runs at the average speed of the previous two hours, how many hours will it take to reach City B? 60 △ 1-1 / 6 = 72 km / h (60 + 72) △ 1 / 8 = 1056 km (60 + 72

From a point O in space, three line segments with 60 angles are introduced, OA = 1, OB = x, OC = y. if x + y = 4, the maximum volume of o-abc is 0
A. Root 2 b. (root 2) / 6 C. (root 2) / 3 d. (root 2) / 3

Let D imagine the OBC plane as a horizontal plane, and the distance from point a to the plane is certain. Using the projective theorem, we can find that it is actually equivalent to the height of a regular tetrahedron with side length 1, which is the volume of (radical 6) / 3 tetrahedron o-abc = 1 / 3 * (radical 6) / 3 * OBC area, and the OBC area is 1 / 2 * sin60 * ob * o

For a batch of goods, 20% of them were transported in the first time, 6 tons in the second time, and 2 tons less than the sum of the previous two times in the third time. At this time, there are still 3 / 1 of them, how many tons in total

Let x tons in total, 20% X for the first time and 20% x + 6-2 tons for the third time
20%x+6+20%x+6-2=（1-1/3）x
X = 37.5 tons

The maximum value of function y = Log1 / 2 [x + 1 / (1 + x) + 1] (x > 1) is (1 / 2 is the base)

y=log1/2[x+1/(1+x)+1] (x>1)
=log1/2[(x+1)+1/(1+x)]
Because x > 1, according to the monotonicity of the sign function
When x + 1 > 2, it increases monotonically,
The inner function increases monotonically, the outer function decreases monotonically, and the compound function decreases monotonically
So y

There are 1008 boys in a school, accounting for 6 / 11 of the total number of students in the school. How many students are there in the school?
There are 1008 boys in a school, accounting for 6 / 11 of the total number of students in the school. How many students are there in the school

6 out of 11 = 1848

Factorization of X & # 178; + 4 (XY-1) + Y & # 178
As above

There is something wrong with the title
It should be X & # 178; + 4 (XY-1) + 4Y & # 178;
x²+4(xy-1)+4y²
=x²+4xy+4y²-4
=(x+2y)²-4
=(x+2y+2)(x+2y-2)

There are 24 people in class 6 (1), accounting for 3 / 5 of the class. How many people can reach the standard to make the standard rate reach 75%?
Write the formula

There are X students in the class
（3/5）X=24 X=40
40*75%=30
30-24=6
So there are six less

4x2 + 12xy + 9y2 = 1x2 + 2XY + y2-4 = 0 4x2-9y2 = 0 x2-2xy + y2-1 = 0 (solving equations)

∵4x2+12xy+9y2=1 ∴ (2x+3y)ˆ2=1
∵x2+2xy+y2-4=0 ∴ (x+y)ˆ2=4
∵4x2-9y2=0 ∴ (2x+3y)(2x-3y)=0
∵x2-2xy+y2-1=0 ∴ (x-y)ˆ2=1
Let's find out for ourselves