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1. Car a and car B go opposite each other from a and B at the same time. When they meet, car a goes 2 / 7. When they meet, they go on, return to their destination immediately, and meet again on the way. How many parts of the whole journey is the meeting place from a? A journey is divided into three sections: uphill, flat road and downhill. The length ratio of each section is 1:2:3. The time ratio of a person walking this section of road is 4:5:6. It is known that his uphill speed is 3km per hour, and the total length of the journey is 50km. How many hours does it take him to complete the whole journey?
1. If a goes 2 / 7 and B goes 5 / 7, then B's speed is 2.5 times of a's. suppose the length of the whole journey is s. when a arrives at the destination, B should go 2.5 s. that is to say, B goes from B to a, and then from a to B. now B is in the normal place from B to a, The two cars meet for the first time after arriving at the destination. At this time, the whole journey of the two cars is 5S. A takes 5S * 2 / 7 = 10s / 7, B takes 5S * 5 / 7 = 25s / 7, and finally B starts from a, so the distance between the meeting point and a is the fraction of 25s / 7, 4S / 7, that is, the whole journey from a is 4 / 7
Of course, maybe I want to be complicated. I don't know what the original problem is. If the original problem is to continue walking after meeting, just turn back at the end, and then find the location of meeting again, it will be simple. Just solve the equation as follows: X / (x + 1) = 2 / 5, x = 2 / 3, that is, 2 / 3 of the whole distance from a
2. The whole journey is 50 km, the distance length ratio is 1:2:3, the distance is 25 / 3, 50 / 3, 25, the uphill time is 25 / 3 / 3 = 25 / 9 hours, the time ratio is 4:5:6, so the total time is 25 / 9 * (4 + 5 + 6) / 4 = 125 / 12 hours
If you don't see clearly, I can add
An elementary and intermediate mathematics problem, please answer!
Title: [if P is a point on a semicircle o with ab as diameter, find ∠ APB]
Should be related to Pythagorean theorem, the answer should be 90 degrees!
Connect Po
Because OA = op
Therefore, OAP = OPA
Similarly, OPB = OBP
Therefore, OAP + OPA + OPB + OBP = 2 OPA + 2 OPB = 180 degrees
Therefore, OPA + OPB = 90 degrees
Party A and Party B drive from ab at the same time. After 4 hours, the two cars meet on the way. After meeting, they continue to advance at the same speed. After another 5 hours, Party B just arrives at place a, and Party A exceeds 40 kilometers from place B. how many meters did party B drive when Party A arrives at place B?
It took Party B 4 + 5 = 9 hours to complete the whole journey, dividing the journey into 9 equal parts. When Party A and Party B met in 4 hours, Party A walked 5 / 9 and Party B walked 4 / 9,
That is, the speed of B is 4 / 5 of that of A;
9 hours, a left (9 / 4) × (5 / 9) = 5 / 4, [b left (9 / 4) × (4 / 9) = 1 ~ that is, the whole process, just for ten understanding
So the extra quarter of a is 40 km
The total length of a and B is 40 × (5 / 4-1) = 160 km, so when a arrives at B, B drives 160 × (4 / 5) = 128 km
The answers in the exercise book are as follows:
40 ÷ (5 / 4-1) × (4 / 5) = 128 km
Given that the line y = KX + 5 is parallel to the line y = 3x, what is the analytical expression of the changed line?
Casually ask, under what circumstances two linear function line parallel, please say, class can not hear clearly, ha ha
y=3x+5
When k is equal, parallel
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