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A problem of mathematics in grade one of junior high school If someone rides a bicycle from place a to place B, if the speed is 1 kilometer faster than usual, he can arrive 7 minutes earlier. If he is 1 kilometer slower per hour, he will arrive 8 minutes later. Find out the speed of the person's bicycle and the time it takes for him to get to place B Binary linear equation solution!
If the speed of this person is x km / min, and the speed of this person is y min, then
(x+1)(y-7)=xy①
(x-1)(y+8)=xy②
The solution is: x = 15, y = 112
A: the speed of a person's bicycle is 15 km / min; the time from a to B is 112 minutes
Mathematics problems in grade one of junior high school
Xiaoqiang's house and Xiaoyong's house are 11km apart, and they ride bicycles to each other's house. If they start at the same time, they will meet on the road 30 minutes later; if Xiaoqiang starts 22 minutes later, Xiaoyong starts 20 minutes later. Q: what's the speed of their bicycles,
Let Xiaoqiang's speed be V1 and Xiaoyong's speed be v2
(V1 + V2) x30 = 11, they travel at the same time, speed and X time = total distance
V1x (22 + 20) + v2x20 = 11 Xiaoqiang started 22 minutes ahead of time. Xiaoqiang was still walking when Xiaoyong started. Xiaoqiang walked 42 minutes and Xiaoyong walked 20 minutes when Xiaoyong met
V1 = 1 / 6 km / min V2 = 1 / 5 km / min
A city's mobile communication company has set up two kinds of communication services: the user of globetron pays 50 yuan monthly basic fee first, and then pays 0.4 yuan for each minute of the call; Shenzhouxing does not pay the monthly basic fee, and pays 0.6 yuan for each minute of the call (here refers to the call in the city). If the call takes X minutes in a month, the two kinds of communication costs are Y1 yuan and Y2 yuan respectively
(1) Make their images in the same rectangular coordinates
y1=50+0.4x
y2=0.6x
Function relations have been listed, the image can only be drawn by itself
The quadrilateral ABCD is a parallelogram. The circle O with diameter of CD and ab is tangent to point D, and a point E is on the circle. De intersects AB, and the angle AED = 45 degrees
If the radius of circle O is 3cm, AE = 5cm, calculate the angle ade and sine value
Connect: be, then the quadrilateral abed is a circular inscribed quadrilateral,
So: ∠ ade + ∠ Abe = 180 ° i.e. ∠ ade = 180 ° - Abe
So: sin ∠ ade = sin (180 ° - ABE) = - sin ∠ Abe
And: ∠ AEB = 90 °, AE = 5cm, ab = 6cm
So: sin ∠ Abe = 5 / 6
So: sin ∠ ade = - 5 / 6
24 point questions 3,4, - 6,10
3×（4-6+10）
The two trains set out from a and B and met at 48km away from the terminal four hours later. It is known that the local train is 5 / 7 of the speed of the express train. What is the speed of the two trains?
How many kilometers is the distance between the two places? Article 2: 1000 + 999-998-997 + 996 + 995-994-993 +. + 104 + 103-102-101 Article 3: a batch of parts can be completed by Party A and Party B in cooperation with 12 groups. After a few days of cooperation, Party B asks for leave because of business, and Party B only completes 3 / 10 of the total. It takes 14 days for Party A to complete the work. How many days does Party B ask for leave, It is required that the bottom radius is 6 decimeters, and the ratio of height to bottom radius is 3:1. How many square decimeters does it take to make 10 such oil drums? The calculation process should be written
1) Because the slow train is 5 / 7 of the speed of the fast train, the distance of the slow train is 5 / 7 of the distance of the fast train
If the whole journey is divided into 12 parts, then the fast train runs 7 parts, that is, 7 / 12 of the whole journey, and the slow train runs 5 parts, that is, 5 / 12 of the whole journey
When meeting, the distance from the midpoint accounts for (7 / 12-1 / 2) = 1 / 12 of the whole journey
Therefore, the whole journey is 48 △ 7 / 12-1 / 2 = 48 △ 1 / 12 = 576 km
The speed of the express is: 576 * 7 / 12 △ 4 = 84 km / h
The speed of local train is 576 * 5 / 12 △ 4 = 60 km / h
2）1000+999-998-997+996+995-994-993+.+104+103-102-101
=4+4+.+4=4*25*9=900
3) There are too many typos, which leads to the unclear meaning of the title
4) Bottom radius: 6 decimeters
Height: 6 * 3 = 18 decimeters
Surface area = 2 * bottom area + side area = 2 * 36 π + 12 π * 18 = 72 π + 216 π = 288 π
Iron sheet required for 10 oil drums: 288 π * 10 = 2880 π square decimeter
Do not know you ask, if you understand, please timely adopt
If the distance between the middle point of the bottom of an isosceles triangle and a waist is 5cm, how high is it?
If the distance between the middle point of the bottom of an isosceles triangle and a waist is 5cm, how high is it?
Let this triangle be ABC, BC be the base, d be the midpoint of BC, and ED be the vertical line passing through point D and AC,
The high line BF of waist AC intersects AC with F, so FB is parallel to ED, and triangle CDE is similar to triangle CBF, so FB / ed = BC / CD = 2, that is FB / 5 = 2, FB = 10
The waist height is 10
Given X / 3 = y = Z / 2 (not equal to 0), find XY + YZ + ZX / x ^ 2-3y ^ 2 + 4Z ^ 2
From X / 3 = y = Z / 2, we can get x = 3Y, z = 2Y and substitute it into the formula
xy yz zx/x^2-3y^2 4z^2
=（3 2 6）y^2/(9-3 16)y^2
=11/22
=1/2
Wish: every year has today, every year has today, every month raises salary, every week Wins Lottery, every day good mood, every day good luck way, day meets God of wealth, night count money
The formula of tree planting problem
Tree planting problem 1 tree planting problem on non closed line can be divided into the following three cases: (1) if trees are to be planted at both ends of the non closed line, then: number of trees = number of segments + 1 = total length △ spacing + 1 total length = spacing × (number of trees-1) spacing = total length △ number of trees-1. (2) if trees are to be planted at one end of the non closed line, the other end
When the side length of a square increases by 3cm, its area increases by 39cm2. The side length of the square is ()
A. 5cmB. 6cmC. 8cmD. 10cm
Let the original side length of the square be x, then x2 + 39 = (x + 3) 2, the solution is x = 5, so a
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