If A2 + a3 = 4, then S4=

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• 1. If A2 = 1, A3 = 3, then S4=______ ．
• 2. If the cubic power of 4x minus the square of 2x, the quadratic power of Y minus the square of N plus the quadratic power of Y is a quartic polynomial, find the cubic power of half n (n-1) + 3N If the cubic power of 4x-2x is a quartic polynomial, the cubic power of half n (n-1) + 3N can be obtained
• 3. If there are three common forces of 3N, 5N and 6N, then their resultant force () A. It may be zero. B. it may not be zero. C. the resultant force must be in the direction of 6N. D. the resultant force must be opposite to the direction of 3N
• 4. If the three forces are 5N, 3N and 7n respectively, the maximum of their resultant force is?
• 5. The magnitude of the two forces are 3N and 5N, respectively Can the resultant force be 3N or 5N
• 6. Three forces: 3N, 4N and 5N
• 7. Can a 2n force be decomposed into 6N and 3N components
• 8. Given the magnitude of a force 30n, decompose the force into two components. What are the magnitude of these two forces? A 10N, 10N B 20n, 40n C 200N, 200N D 700n, 720n multi topic selection which? Helper analysis That's how to calculate it? How to analyze 720-700, how to get 30
• 9. A vertical downward 8N force is decomposed into two forces, one of which is horizontal in direction and 6N in magnitude, and the other is horizontal in magnitude
• 10. Under the action of two mutually perpendicular forces F1 = 6N and F2 = 8N, the object moves 10m along the direction of their resultant force 1. How much work does the force F1 and F2 do to the object? 2. How much work does their resultant force do to the object?
• 11. If A2 = 1, A3 = 3, then S4 = () A. 12B. 10C. 8D. 6
• 12. Known: in the arithmetic sequence {an}, A3 + A4 = 15, a2a5 = 54, tolerance d < 0, the second question 1) Finding the general term formula an of sequence {an} 1、 The arithmetic sequence is A2 + A5 = A3 + A4 = 15 a2a5=54 By Weida theorem A2, A5 are the equations X & # 178; - 15x + 54 = 0 x=6,x=9 d
• 13. Known: in the arithmetic sequence {an}, A3 + A4 = 15, a2a5 = 54, tolerance d < 0 Find the maximum value of [Sn - (an-3)] / N and the corresponding value of n Ans:n=4 In this case, ymax = 15 / 2
• 14. It is known that {an} is an arithmetic sequence with a tolerance of 2, and A1, A3 and A4 are proportional sequences, then the sum of the first nine terms of the sequence {an} is equal to () A. 0B. 8C. 144D. 162
• 15. The tolerance of arithmetic sequence an d = 1 / 2, and S100 = 145, find a1 + a3 + A5 +. + A99 Why: M2 = A2 + A4 + A6 +... + A100 = a1 + a3 + A5 +... + A99 + (1 / 2) × 50 How does this (1 / 2) × 50 come from?
• 16. In the arithmetic sequence {an}, d = 12, S100 = 145, then a1 + a3 + A5 + +The value of A99 is () A. 57B. 58C. 59D. 60
• 17. If the tolerance of arithmetic sequence {an} d = 1 / 2, a1 + A2 + a3... + A99 = 60, calculate S100
• 18. Given that the sequence {an} is an arithmetic sequence, the sum of the first n terms Sn = n ^ 2, find the value of a1 + a3 + A5 + A7 +. + a25
• 19. Given that the sum of the first n terms of the arithmetic sequence {an} is Sn = 2n & # 178; - 10N, find the values of (1) A1 and A3; (2) find A5 + A6 + A7 + A8; (3) find its general term formula and judge whether it is arithmetic sequence
• 20. Only the first N-term sum formula of the sequence {an} is Sn = (3) ^ n - 1, the general term formula of {an} is obtained, and it is proved that {an} is an equal ratio sequence