. = = Lim 1 / (x ^ 2-3x + 2) find the limit value,

When y = 1-x transforms, y tends to zero,
lim sin(π-πy）/（y^2+y)=lim sin(πy）/（y^2+y)=π

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1. The limit of ((3x + 1) / (3 + x)) ^ (1 / (x-1)) when x tends to 1
2. If the equation of motion of a body is s = 7T ^ 2-13t + 8, then its instantaneous velocity at t = () is 1 Note: if the interval is | T, t + △ x |, then △ y = 7 △ x ^ 2 + 14T △ x + 7T ^ 2-13t-13 △ x + 8-7t ^ 2 + 13t-8 = 7 △ x ^ 2 + 14T △ x, then △ Y / △ x = 7 △ x + 14T, so 14T = 1, t = 1 / 14. But the answer is 1?
3. A math problem of Liberal Arts in senior two. (Application of derivative) A manufacturer manufactures and sells a kind of beverage in spherical bottles. The manufacturing cost of the bottle is 0.8 π R ^ 2, where R is the radius of the bottle, and the unit is cm. It is known that the manufacturer can make a profit of 0.2 points for every 1ml of beverage sold, and the maximum radius of the bottle that the manufacturer can manufacture is 6cm Q: (1) what is the radius of the bottle to maximize the profit of each bottle? (2) When the bottle radius is large, the profit of each bottle is the smallest? Please write the process, thank you
4. It is known that the derivative of F (x) is 2x ^ 2-4ax-3. If f (x) has and only has one extreme point in (- 1,1), the value range of a is obtained
5. Find the sum of all integer solutions of the system of inequalities 5 ＞ 2 (1 − x) − 13X ≤ 23 − X
6. Solve the system of inequalities x + 1 ＞ 0. X ≤ (X-2 / 3) + 2, and write the largest integer solution of the system of inequalities
7. In the "beautiful Urumqi" activity, a community decided to use 9000 pots of chrysanthemum and 8100 pots of sunflower with a and B gardening styles, a total of 100 flowers were placed in the community. The flowers required for each gardening style are shown in the following table: & nbsp; & nbsp; need chrysanthemum (pot) need sunflower (pot) & nbsp; a shape & nbsp; & nbsp; 100 & nbsp; 60 & nbsp; A B shape & nbsp; 80 & nbsp; Based on the above information, let's set X horticultural models of type A to answer the following questions: (1) please write out the inequalities that meet the meaning of the problem and find out the solution set; (2) if the cost of matching a horticultural model of type A is 600 yuan and that of matching a horticultural model of type B is 800 yuan, try to determine how many of the models of type a can make the cost of the 100 horticultural models the lowest
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10. Inequality and inequality group mathematical problems In a competition, a shooter hits 54 rings in the first six shots. If he wants to break the record of 91 rings (10 times), how many rings can he have in the seventh shot? (2) if the seventh shot is 8 rings, how many times must he hit 10 rings in the last three shots to break the record? (3) if the seventh shot is 10 rings, Do you have to hit 10 rings at least once in the last three shots to break the record?
11. If x2-3x + 1 = 0, the value of fraction x2 / (x ^ 4 + x2 + 1) is Ask God for help!
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14. Given a = {(x, y) | x2 + y2-6x-8y + 20 = 0}, B = {(x, y) | kx-y-4k + 3 = 0}, then the number of elements of a ∩ B is () A. 0B. 1C. 2D. 3
15. If M = {y | y = x2 + 1}, n = {y = | y = 3-x2}, then M intersects n =?
16. Set a = {y | X & # 178; + 2x, - 2 ≤ x ≤ 2} B = {x | X & # 178; + 2x-3 ≤ 0} take any element a in set a, then what is the probability that a belongs to B Eager for answers
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