Calculate [1 / 3-1 / 2] + [1 / 4-1 / 3] + [1 / 5-1 / 4] + +【1/2004-1/2003】

Calculate [1 / 3-1 / 2] + [1 / 4-1 / 3] + [1 / 5-1 / 4] + +【1/2004-1/2003】

Solution; [1 / 3-1 / 2] + [1 / 4-1 / 3] + [1 / 5-1 / 4] + +【1/2004-1/2003】
=-[(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+…… +(1/2003-1/2004)]
=-[1/2-1/3+1/3-1/4+1/4-1/5+…… +1/2003-1/2004]
=-(1/2-1/2004）=-1001/2004

The two trains travel from two places 670 kilometers apart. Car a travels 70 kilometers per hour, and car B travels 80 kilometers per hour. One hour after car a leaves, car B stops
(next to the top). Just leave. How many hours will the two cars meet?

670-70=600
600/（700+80）=4
So after 4 hours, the two cars met. I hope I can help you,

X + 4 / 3 = 2x / 3, 36-2x / 3 = 18,

x＋4/3＝2x/3
3x＋4＝2x
x＝－4
36－2x/3＝18
36－18＝2x/3
18＝2x/3
2x＝54
x＝27

The speed ratio of the two vehicles is 4; 3AB
How many kilometers apart

The speed ratio between a and B is 4; 3
Then the speed of car B is 80 * 3 / 4 = 60
So the distance between AB and ab is (80 + 60) * 7 = 980km

Move the decimal point of a decimal one place to the right, and the difference with the original number is 34.56. What is the original number?

Original number
34.56÷（10-1）=34.56÷9=3.84
If you have any new questions, please don't send them in the form of follow-up questions, send them to me for help or send them to the question link address,

At the same time, the passenger car and freight car drive in the opposite direction from the midpoint of a and B. after 3 hours, the passenger car arrives at a place, and the freight car is 42 kilometers away from B place. The ratio of cargo to passenger speed is 3:5
How many kilometers are there between a and B?

At the same time, the passenger car and the freight car drive in the opposite direction from the midpoint of a and B. after 3 hours, the passenger car arrives at a place, and the freight car is 42 km away from B place
The passenger speed ratio is 3:5, so the distance ratio is 3:5. How many kilometers are there between a and B?
Distance between truck and B: total distance = 5-3: 5x2 = 2:10 = 1:5
Distance between a and B = 42 x 5 = 210 km

The position of the real number P on the number axis is shown in the figure, simplifying (P − 1) 2 + (P − 2) 2=______ ．

According to the number axis, 1 ＜ P ＜ 2, ∩ P-1 ＞ 0, P-2 ＜ 0, ∩ P − 1) 2 + (P − 2) 2 = P-1 + 2-P = 1

The length of the two trains is 144m and 180m respectively. Car a travels 4m more than car B every second. It takes 9 seconds for the two trains to travel in opposite directions. What's the speed of the two trains? If they travel in the same direction, how many seconds does it take for car a's head to overtake car B from the tail of car B and to the end of car a?

If the velocity of a is x and B is x-4, then (x + x-4) * 9 = 144 + 180, solution x = 20, a is 20 and B is 16
（144+180）/4=81

The average number of the three numbers is 60, and the ratio of the three numbers is 2:3:5. What is the largest number among the three numbers?
Thank you very much

The sum of the three numbers is 60 × 3 = 180. The largest of the three numbers is
180÷(2+3+5)×5=90

The speed ratio of a and B vehicles is 5:6. The two vehicles are facing each other at the same time from station AB, and they meet at 4km away from the midpoint. How about the distance between the two stations?

From the speed ratio, we can know that car a runs 5 / (5 + 6) = 5 / 11 of the whole journey, just as car B runs 6 / 11
4 × 2 = 8 km
So 8 (6 / 11-5 / 11) = 88 km
Find out the distance between the two stations