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The distance between a and B is 40 km, the speed of motorcycle is 45 km / h, the speed of truck is 35 km / h, and the speed of truck is 35 km / h How long does it take for the same car to travel in opposite directions? The distance between the two cars is 10 kilometers?
Two cases
1: No meeting, no distance
Need: (40-10) / (45 + 35) = 3 / 8 hours
2: Distance after meeting
Need: (40 + 10) / (45 + 35) = 5 / 8 hours
Given the equations of a, B {4a-3b = 3C, a-3b = - C, and a, B is not equal to 0, find: 1. A: B: C 2.2b + B-C / C
Questions 5 and 6 on page 90 of Mathematics
I want the specific process
According to the question, 4a-3b = - 3 * (a-3b), then 7a = 12b, (a, B is not equal to 0)
Let a = 12, B = 7, then C = 9
a:b:c=12:7:9
2.(2a+b-c)/c=(24+7=9)/9=32/9
Car a and B leave from a and B at the same time. Car a travels 50 kilometers per hour, and car B travels 40 kilometers per hour
How many kilometers is the distance between a and B?
At 40 km away from the midpoint, fast armour opened 40 * 2 = 80 km more
Time 80 / (50-40) = 8 hours
(50 + 40) * 8 = 720km
A: A and B are 720km apart
Given that the solution of equation 6x-3-2m = 2x-7 is greater than 2 and less than 10, then the value range of M is?
The solution of the equation is x = (m-2) / 2
A and B travel 360 kilometers apart from each other at the same time. They meet 7.2 hours later. A's speed is three times that of B's. how many kilometers does B travel per hour?
360 △ 7.2 △ 3 + 1, = 50 △ 4, = 12.5 km; a: B travels 12.5 km per hour
The decimal point of a decimal is moved one place to the left, and the number obtained is 2.52 less than the original number?
Let the original decimal be X
X—0.1X=2.52
The solution is x = 2.8
A: the number is 2.8
A and B from a to B, a speed of 80 meters per minute to catch up with the first start of B, known to B 65 meters per minute. A with 20 minutes to catch up with B. B than a set out first
Let B start X minutes first, 65x = (80-65) * 20
dedekind cut
1. How does dedkin define irrational numbers
2. What is the meaning of the definition and the main progress compared with the previous explanation
"When we consider a partition (a, b) which is not generated by rational numbers, we get a new number, namely irrational number a, which is completely determined by partition (a, b)" Does he mean that both sides of irrational numbers are rational numbers?
I still don't understand. Do you have his old man's book?
In analytic function, the definition of real number is to define positive rational number from natural number, and then to define real number through infinite sets of rational numbers. Now, we usually use the construction method of dedkin and Cantor
A. B two trains run from a and B, which are 357.5 km apart. Train a runs 75 km per hour, while train B runs 68 km per hour. How many hours do they meet?
Let a and B meet in X hours
X=357.5/（75+68）
X=357.5/143
X = 2.5 hours
A: the two cars met in 2.5 hours
The average number of a, B and C is 70. The ratio of a, B and C is 5:6:3. What are the numbers of a, B and C
The sum of the three numbers of a, B and C is 70 * 3 = 210
Then a = 210 * 5 / 14 = 75
B = 210 * 6 / 14 = 90
C = 210 * 3 / 14 = 45
This is my conclusion after meditation,
If I can help you, I hope you will give me a satisfactory answer
If not, please ask, I will try my best to help you solve it~
The answer is not easy. If you are not satisfied, please understand~
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