Sequence: 2,4,7,11,16,22,29 Then the general term an =?

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• 1. The following equations can be obtained by calculation: 22-12 = 2 × 1 + 1, 32-22 = 2 × 2 + 1, 42-32 = 2 × 3 + 1,..., (n + 1) 2-n2 = 2 × n + 1. Add the above equations to get: (n + 1) 2-12 = 2 × (1 + 2 + 3 +...) +n) 1 + 2 + 3 + +N = n (n + 1) 2 analogy above: please find 12 + 22 + 32 + +The value of N2 (it is required that there must be an operational reasoning process)
• 2. 1. Fibonacci sequence is 1, 1, 2, 3, 5, 8, 13 What is the difference between the 100th term and the sum of the first 98 terms 2. There are two gears meshing with each other as shown in the figure. A straight line with an arrow is drawn on each gear. At the beginning, the two arrows are just opposite. Then the small wheel rotates clockwise. If the big wheel has 177 teeth, the two arrows meet again after the small wheel rotates
• 3. Sequence - 1,3, - 2, - 4,11, ()
• 4. 1. Sequence: 1, - 2,3, - 4 What is the sum of the first 99 items of (- 1) ^ (n-1)? 2. Equal ratio sequence 1, A1, A2, A3 Then A1 * A2 * A3 * *a2n=?
• 5. Find the first n terms and S N of sequence 1 * 2 / 2,2 * 3 / 2,3 * 4 / 2,4 * 5 / 2
• 6. 4 12 24 40 60 according to what rules
• 7. 12.21 13.41 25.81 38.161 () what's in brackets? RT I got it. 63.321 Experts help me identify, right?
• 8. Observe the sequence 6, 7, 9, 13, 21, then fill in the rule on the horizontal line (that is, the next number)
• 9. 1. All odd numbers except 1 are grouped by one, two, three and four circulations: (3), (5,7), (9,11,13), (15,17,19,21), (23), (25,27), (29,31,33), (35,37,39,41), (43),. Then, what are the numbers in the brackets in 2011?
• 10. 1. What's the rule of 5, 17, 49? It's about sequence
• 11. What kind of function or sequence is 1,2,4,7,11,16,22,29? Who can use an equation to express the increasing relationship?
• 12. The circumference of a rectangle is 88cm, and the ratio of length to width is 7 to 4. How many centimeters are the length and width of the rectangle? How many square centimeters is the area? In order to support the drought stricken areas in Southwest China, the school carried out the theme activity of "love for drought stricken areas". The students collected waste mineral water bottles and donated the money to the disaster area. The students of class 62 were divided into three groups to collect mineral water bottles. The ratio of the number of bottles collected by the first group and the second group was 4:3, The ratio of the number of bottles collected by the second group and the third group is 6:5. What is the ratio of the number of bottles collected by the three groups?
• 13. 69 10 One day, Uncle Li works 4 hours in the morning and 3 hours in the afternoon, processing 1400 parts. If Uncle Li's work efficiency remains unchanged, how many parts does he process in the morning?
• 14. A cylindrical container with a bottom radius of 10 cm holds 27 cm high water. Put it into a stone. After immersion, the height of the water surface rises to 35 cm. What is the volume of this stone?
• 15. 1. Zhao Wei's movie ticket is "No.4, row 11", abbreviated as (11,4). If Li Ming's position is (3,6), then how many rows is the distance between Zhao Wei and Li Ming? 2. Draw the largest circle in a square. What percentage of the area of the circle in the square? 3. In a square grassland with a side length of 10 meters, there is a tree at the two ends of a diagonal line. Each tree is tied with a cow. The rope length is 10 meters. How many square meters of grassland can both cows eat?
• 16. One week later, kiosk a reduced the price by 15%, and another week later, kiosk B increased the price by 30%. Kiosk B only raised the price by 15% two weeks later. Which one of kiosks A and B sold more in two weeks? 2. Our body needs to take in 2500 ml water every day. 48% of the water is from food, and the rest is from drinking water. How much water does the human body get from drinking water every day?
• 17. A cylindrical tin oil barrel is filled with gasoline. Pour 2 / 3 of the gasoline in the barrel, and there are 36 liters left. It is known that the height of the oil barrel is 8 decimeters, and what is the bottom area of the oil barrel? To pave a piece of land, it's 2400 fast to use 3-decimeter-long square bricks, but how fast to use 2-decimeter-long square bricks instead
• 18. There are 34 people playing on the 11 table tennis tables. How many tables are there in singles and doubles?
• 19. My father is 28 years older than Xiao Liang. Seven years later, my father's age is just three times that of Xiao Liang. How old are my father and Xiao Liang after seven years?
• 20. My father is 28 years older than Xiao Liang. Seven years later, my father's age is just three times that of Xiao Liang. How old are my father and Xiao Liang after seven years?