Solve the equation. 3x + 3 / 7 = 10 / 7

Solve the equation. 3x + 3 / 7 = 10 / 7

3x + 3 / 7 = 10 / 7
3x = 10 / 7-3 / 7
3x=1
X = 1 / 3

3x + 7.5x0.4 = 10.5, please help me solve the equation

3x+7.5X0.4=10.5
Solution 3x + 3 = 10.5
3x=10.5-3
x=2.5

Given the positive proportion function y = (a ^ 2-2a) x ^ 2A ^ 2-5A + 3, find the value of A

Because it is a positive proportional function, then 2A ^ 2-5A + 3 = 1 and a ^ 2-2a is not = 0
That is, 2A ^ 2-5A + 2 = 0, a (A-2) does not = 0
(2a-1) (A-2) = 0, a does not = 0 or 2
a=1/2,a=2
To sum up, a = 1 / 2

A large car and a small car both drive from a to B. the speed of a large car is 80% of that of a small car. It is known that a large car starts 17 minutes earlier than a small car, but stops 5 minutes at the midpoint of two places before continuing to drive to B. However, the small car does not stop midway after starting, and drives directly to B. finally, the small car arrives at B 4 minutes earlier than a large car. It is also known that the large car starts at 10 am When did the car catch up with the big one in the morning

It takes 17-5 + 4 = 16 minutes for a large car to complete the whole journey; it takes 16 ÷ (1-80%) = 80 minutes for a large car to complete the whole journey; it takes 80 × 80% = 64 minutes for a small car to complete the whole journey. After the big car starts, it reaches the midpoint in 80 ÷ 2 = 40 minutes and leaves in 40 + 5 = 45 minutes. The small car starts 17 minutes after the big car starts. When it reaches the midpoint, the big car has already gone 17 + 6 4 △ 2 = 49 minutes. It means that when the car reaches the midpoint, the bus has started again. Then it is in the back half of the road to catch up. Since both of them didn't rest later, the bus arrived 4 minutes earlier than the bus. Then the time to catch up is 4 △ 1-80% × 80% = 16 minutes before the bus arrived, so it is 17 + 64-16 = 65 minutes after the bus started At this time, the time is 10:00 + 1 hour and 5 minutes = 11:05. A: then the car caught up with the big car at 11:05 in the morning

M + n = 5 Mn = 3 find the square of (m-n)

(m-n)²
=(m+n)²-4mn
=5²-4×3
=35-12
=13

The car travels 48 kilometers per hour and the train 80 kilometers per hour. What percentage of the speed of the train is that of the car?
Be quick
What's the formula

Standard formula:
Vehicle speed: 48km / h
Train speed: 80km / h
A train is a percentage of the speed of a car:
a=80km/h/48km/hx100%=80/48x100%=167%

At 1, 2, 3 In 499 and 500, the number 2 appears______ Times

There are 20 in 1-99 (22 has 2 2), 20 in 100-199, 100 in 200-299 (2 in 100), 20 in 20 (2 in 10), 20 in 300-399 (322 has 2 2), and 20 in 400-499 (422 has 2 2). Therefore, a total of 20 × 4 + 100 = 200

Airplane flight
The plane is flying near the surface of the earth at a speed of 320km / h. which of the following situations can the passengers on the plane see the sun stopping in the air for a long time? (r = 6400km, cos11 ° = 0.98, cos79 ° = 0.19) A. flying from east to west at 79 ° n B. flying from west to east at 79 ° n C. flying from west to east at 11 ° n D. flying from west to east at 11 ° n

At 79 degrees north latitude, according to the solution of T = 2 π R / V (r = R earth · cos79, t = 24h), we get V ≈ 318km / h. because the earth's rotation is from west to East, the plane must move from east to west to see the sun not moving. At 79 degrees north latitude, the plane's velocity is just close to the earth's linear velocity

The difference between three times of a number and one-third of the number is 10

Suppose that the number is X
3x-1/3 x=10
8/3x=10
x=15/4

Can friction change the direction and magnitude of velocity
1
2. In the four basic interactions, can the interacting objects not contact or must not

1. Turn off the engine, the car will slow down. That is, the friction changes the speed
When a car "turns" on a horizontal road, friction changes the direction of speed
2. Interacting objects may not touch
For example, if the earth is attracted by the sun, it will not contact with the sun
Another example is that objects falling in the air are attracted by the earth and do not touch the earth