![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
Let the sum of the first n terms of the arithmetic sequence {an} be SN. If S1 ≤ 13, S4 ≥ 10, S5 ≤ 15, then the maximum value of A4 is () A. 3B. 4C. -7D. -5
∵ S4 ≥ 10, S5 ≤ 15 ∵ a1 + A2 + a3 + A4 ≥ 10, a1 + A2 + a3 + A4 + A5 ≤ 15 ∵ A5 ≤ 5, A3 ≤ 3, that is: a1 + 4D ≤ 5, a1 + 2D ≤ 3, the sum of the two formulas is: 2 (a1 + 3D) ≤ 8 ∵ A4 ≤ 4, so the answer is 4
When the acceleration a is equal to 0.5m/s2 on the straight road, the car moves with uniform acceleration. When the speed reaches V1 = 10m / s, the power remains unchanged at this time
If the resistance of the car remains unchanged, what is the time required for the car to reach V2 from V1?
Let the mass of the car be m, the traction force F, and the friction force F. from P = FV, we can see that when v = V1, P = Fv1, Ma = f-f is substituted into P = (F + MA) V1, and when v = V2, the maximum speed is reached. The side traction force F is equal to the friction force F, that is, P = f2v2, F2 = f is substituted into P = fv2, and P = (F + MA) V1, P = fv2 is combined with P = (F + MA) V1, P = fv2 to get P = 10m, F = 0.5m
Xiaogang and Xiaoqiang have 128 stamps in total. Xiaoqiang has three times as many stamps as Xiaogang. How many stamps does Xiaogang have? (solved by equation)
If Xiaogang has x stamps, Xiaoqiang has 3x stamps, x + 3x = 128, & nbsp; 4x = 128, & nbsp; & nbsp; X = 32. A: Xiaogang has 32 stamps
How to do the seventh question of 18 aspects of second grade mathematics in happy class
Please write the title. I don't know how to help you with it
On the number axis, point a represents - 4 and point B represents 6. Please bisect line AB to get point C, and then write the number it represents
Divide line AB into five equal parts to get D, e, F and g respectively, and then write out the numbers they represent
Divide the line AB into three equal parts to get the points m and N respectively, and then write out their respective numbers
-2,0,2,4;
-2/3,8/3
What can be measured directly at a short distance on the ground
When there is a short distance on the ground, you can use () or () to measure it directly. When there is a long distance on the ground, you should first measure a line () through the two points, and then measure the distance between the two points along (). When there is no measuring tool or the measurement result is not very accurate, you can also use () or ()
Tape measure or tape measure
Straight line. Origin
Visual inspection and walking
If 2x ^ my ^ P is the same as 3x ^ NY ^ Q, then
A,m=q,n=p
B,mn=pq
C,m+n=p+q
D. M = n and P = q
No one will
Said the team had a reward
The answer is C
6 cubic meters, 60 cubic decimeters = () cubic meters, 230 cubic decimeters = () cubic centimeters
The volume of a cone is 30 cubic meters, the bottom area is 10 cubic meters, and the height is () meters
The volume of a cylinder is 27 cubic decimeters. Cut it into a cone with the same height as its bottom. The volume of a cone is () cubic decimeters
When the radius of the bottom of the cylinder increases three times and the height decreases three times, the volume of the cylinder increases () times
The bottom radius of the cylinder is 20cm, the side is just a square, and the height of the cylinder is () cm
6 cubic meters, 60 cubic decimeters = (6.06) cubic meters, 230 cubic decimeters = (230000) cubic centimeters. The volume of a cone is 30 cubic meters, the bottom area is 10 cubic meters, and the height is (9) meters. The volume of a cylinder is 27 cubic decimeters. Cut it into a cone with the same height as its bottom, and the volume of the cone is (9) cubic meters
A passenger car and a freight car run from both sides of a and B at the same time. When they meet, the passenger car runs 70 kilometers more than the freight car. It is known that the speed ratio of the passenger car and the freight car is 7:5, and the distance between a and B is 70 kilometers______ Kilometers
7 + 5 = 1270 ^ (712-512), = 70 ^ 16, = 420 (km); answer: the distance between a and B is 420 km
Let X be greater than or equal to 1. Compare the cube of X with the square of x minus x plus 1
x^3-(x^2-x+1)
=x^3-x^2+x-1
=(x-1)(x^2+1)>=0
x^3>=x^2-x+1
RELATED INFORMATIONS
- 1. (- x ^ 2 + 8 + 5x ^ 3) + (- 2x ^ 3 + 5x-7) where x = - 2
- 2. The store bought a batch of 25 cases of drinks, sold 6 cases and 8 bottles on the first day, and there were 220 bottles left. How many bottles are there in all?
- 3. The two trains run in opposite directions from 580 kilometers away and meet after 5 hours. The speed ratio of the two trains is 14:15 The speed ratio of adding one or two trains all the time is 14:15. How many kilometers do the two trains travel per hour?
- 4. 1. A passenger car and a freight car leave from a and B at the same time. After six hours of meeting, the two cars advance at the same speed, and the passenger car arrives in four hours At this time, how many hours does the truck have to travel to station a? 2. A factory produces a batch of pesticides, which takes 12 days for a and 15 days for B. the two vehicles jointly produce for 7 days, exceeding 42 tons. How many tons of pesticides are planned to be produced? 3. A batch of cement is planned to be produced in 15 days by workshop a alone. If it is produced jointly with workshop B, it will only take 8 days to complete. Now after several days of production by workshop a alone, the remaining tasks will be completed indirectly by workshop B. in this way, it takes 17 days. How many days has workshop B produced? (equation) If you are satisfied, 50 points will be added. Thank you. I am in urgent need! There is a batch of materials to be copied. It takes 11 hours for machine a to copy separately, and 13 hours for machine B to copy separately. When two copiers A and B copy at the same time, due to mutual interference, they print 28 pieces less per hour. Now it takes six hours and 15 minutes for the two copiers to finish printing at the same time. How many copies are there?
- 5. When a pile of cement is transported to the construction site, two fifths of the ton is used for building the wall, three fifths of the ton is used for paving the ground, and one tenth of the ton is left (1) How many tons of cement are used? (2) How many tons of cement are delivered?
- 6. The number a is 10% more than the number B, the number B is 20% more than the number C, and the number a is several percent more than the number C?
- 7. 0.75 + three and a quarter - 9 + 0.125 - five eighths + 0.125 =? Minus 64 divided by three and one-fifth multiplied by five eighths =? One and twenty-four minus brackets three eighths plus one sixth minus three fourths multiplied by twenty-four =? Minus nine and thirty-six thirty-five multiplied by eighteen =? Three and three-four times minus six eleven divided by brackets one twelfth minus one bracket equals minus ninety-eight times minus 0.125 plus ninety-eight times eight eighths One plus minus ninety-eight times five quarters? Hehe, it's a bit too much,
- 8. Xiao Hua read a book. On the first day, he read 18 pages more than 21, and on the second day, he read 16 pages less than 6, with 172 pages left. How many pages are there in this story book?
- 9. The bus from a to B had to run for 7 hours. When the expressway was opened, the road was close to 30 km. The average speed increased by 30 km per hour. It took 4 hours to get to a and B
- 10. It is known that square matrix A of order n satisfies a square = 0. It is proved that e + 3a is invertible and its inverse matrix is obtained
- 11. The rated voltage of the motor is 110V, the rated current is 2.2kW. The resistance of the coil is 0.5 ohm? We need to be quick`
- 12. The lithium battery used on the mobile phone is marked with "3.6V & nbsp; & nbsp; 900mA. H". Please estimate the energy that this battery can store______ J．
- 13. It's not that the ratio of density is equal to the ratio of molar mass In this case, the density of methane should be 16:18 than that of water But the relative density (water = 1) is 0.42
- 14. How to use the parameters on the electric energy meter to calculate the maximum power of the electric appliance allowed to be connected in the circuit And a period of time, the dial of the electric energy meter turns NR, the electric energy consumed by the electric appliance
- 15. What's the use of local boundedness of function limits What's the use of this theorem? To prove inequality? To prove extremum? To prove local continuity? What's the use?
- 16. 2x²-7x+6=0
- 17. Find the equation of the line parallel to the line 3x + 4y-12 = 0 and passing through the point a (2, - 3) Solve the linear equation of the intersection of two lines X + Y-3 = 0 and 2x-y = 0 and perpendicular to the line 3x-4y-12 = 0
- 18. As shown in the figure, given that the sphere o is the inscribed sphere of cube abcd-a1b1c1d1 with edge length of 1, the cross-sectional area of plane acd1 truncated sphere o is () A. π6B. π3C. 66πD. 33π
- 19. It is known that a and B are two points on the line Mn, Mn = 4, Ma = 1, MB > 1. Take a as the center, rotate clockwise to point m, and take B as the center, rotate anticlockwise to point n, so that two points m and N are combined into a point C again to form a triangle ABC (1) Find the value range of X (2) If △ ABC is a right triangle, find the value of X (3) Explore: the largest area of △ ABC Don’t copy
- 20. What are the Pinyin of "Du" in "Zheng Ren Mai Lu"? the man who rather trusted his measurements than placing any confidence in his own feet when buying shoes When Zheng people want to buy shoes, they first measure their feet, and then sit on them. When they arrive at the market, they forget to hold them. When they have got shoes, they say, "I forget to hold them!" when they return to the market, they can't take them. When they return to the market, they say, "why don't you try them?" they say, "you'd rather have faith than confidence." Xun'er № xun'er's answer should be wrong, the first "degree", the text has been phonetic duo