10. A has three common point forces F1 = 2n, F2 = 4N, F3 = 4N, forming an angle of 120 ° with each other, and the resultant force is__________ N. The direction is_____ .

10. A has three common point forces F1 = 2n, F2 = 4N, F3 = 4N, forming an angle of 120 ° with each other, and the resultant force is______ N. The direction is_ .

Answer: 2; opposite to F1

{an} is an equal ratio sequence BN = a3n-2 + a3n-1 + a3n

Because an is an equal ratio sequence, then BN = (a3n-1) & sup3;
Then q = BN + 1 / BN = (a3n) & sup3; / (a3n-1) & sup3;
=（a3n／a3n-1）³
Because an is an equal ratio sequence, so (a3n / a3n-1) & sup3; is a natural number, then BN is an equal ratio sequence

If {BN} satisfies BN = a3n-2 + a3n-1 + a3n, then the sum of {BN} is ()
A. SB. 3SC. S2D. S3

Let the first term of {an} be A1, and the common ratio be q, then s = a11 − Q. ∵ sequence {BN} satisfies BN = a3n-2 + a3n-1 + a3n, ∵ BN + 1bn = a3n + 1 + a3n + 3a3n + 3a3n − 2 + a3n − 1 + a3n = Q3 (a3n − 2 + a3n − 1 + a3n) a3n − 2 + a3n − 2 + a3n − 2 + a3n

RELATED INFORMATIONS

1. All the items of the arithmetic sequence an are positive, A1 = 3, the sum of the first n phases is Sn, the common ratio of BN is an arithmetic sequence of 2, and a3b3 = 56, b5s4 = 768 (1) Formula for finding the general term of an BN (2) Finding the first n terms and TN of {an · BN}
2. The first n terms and Sn of sequence 1 * 1 / 2,2 * 1 / 4,3 * 1 / 8,4 / 1 / 10 are? The first n terms and Sn of sequence 1 * 1 / 2,2 * 1 / 4,3 * 1 / 8,4 / 1 / 16 are
3. Sequence 5.9.14.20.27, find the general term an You're right, but can you give me the process? I'll choose your one as satisfactory
4. A possible formula of sequence 0,1,0, - 1,0,1,0, - 1... Is
5. Limit value of sequence When the common ratio q is less than 1 Lim n tends to infinity a (n + 1) / Sn When Q > 1 Lim n tends to infinity a (n + 1) / Sn
6. If a sequence has odd terms, the sum of odd terms is 81, and the sum of even terms is 72, then the sequence has several terms
7. Let {an} have 2n + 1 terms, the sum of all odd terms is 132, and the sum of all even terms is 129
8. In the arithmetic sequence with 2n terms plus 1, the sum of all odd terms is 165, and the sum of all even terms is 150. Find the value of n, Teacher, I don't understand.
9. In the arithmetic sequence with 2n + 1 terms, if the sum of all odd terms is 165 and the sum of all even terms is 150, then n is equal to () A. 9B. 10C. 11D. 12
10. In the arithmetic sequence {an} with odd terms, s odd denotes the sum of odd terms, s even denotes the sum of even terms, then s odd / s even=
11. There are two equal forces F1 and 2. When the angle between them is 90 degrees, the resultant force is F. when the angle between them is 60 degrees, the resultant force is f_ RT, I figured it out to be 1.5f1 ^ 2 The answer is (√ 6 / 2) F
12. Two components F1 = 3N and F2 = 4N are known. The angle between the two components is 90 degrees. Find the resultant force of the two forces
13. Three forces act on an object with a mass of 2kg at the same time, where F1 = 3N, F2 = 4N, F3 = 2n. The directions of F1 and F2 are always vertical, and the direction of F3 can be changed at will, then the acceleration of the object may be () A. 4m/s2B. 3m/s2C. 2m/s2D. 1m/s2
14. When the two forces are in the same direction, the resultant force is a; when the two forces are in the opposite direction, the resultant force is B. when the two forces are perpendicular to each other, what is the resultant force?
15. When two forces are in the same direction, the resultant force is a, and when the two forces are in the opposite direction, the resultant force is B. when the two forces are vertical, the resultant force is? Write down every step as long as you know why
16. Two mutually perpendicular common point forces F1 and F2 act on the same object and make the object move for a period of displacement. If F1 does 4J work on the object, F2 does 5J work on the object How much work do they work together? Write down the reasons
17. The resultant force of F1 and F2 is F. if the angle between the two forces remains unchanged, when will the resultant force remain unchanged when F1 becomes larger
18. 15. B as shown in the figure, if the magnitude of the three common point forces is F1 = 5N, F2 = 10N, F3 = 15N and θ = 37 ° respectively, the resultant force FX in the X direction=_______ N. On the Y side
19. It is known that F1 = 6N F2 = 7n F3 when a body moves in a straight line with uniform velocity under the action of three different directions of common point forces =8N, what are the three resultant forces? What are the magnitude of the two resultant forces F1 and F2 in the N direction?
20. Among the following four pairs of forces, a2n.11n b.3n.9n c.5n.7n d.7n.13n is impossible to be 8N