1/(1*4)+1/(4*7)+1/(7*10)+…… +1 / [(3n-2) (3N + 1)] summation

RELATED INFORMATIONS

• 1. Let Sn = 1 * 4 + 2 * 7 +. N (3N + 1), then SN=
• 2. Sum: 1 + 45 + 752 + +3n−25n−1．
• 3. An = 3N ^ 2-2n + 1 for Sn =?
• 4. If Sn = 2n ^ 2 + 3n-4, then an=____
• 5. Find sequence 1 + 1, 1A + 4, 1A2 + 7, 1A3 + 10 ，1an-1+（3n-2），… The sum of the first n terms of
• 6. If n is an integer and y = n + 3N ＾ 2 + 2n ＾ 3, we prove that y is a multiple of 6
• 7. Prove n + (n + 1) + (n + 2)... + 2n = 3N (n + 1) / 2 by induction
• 8. Given 3 ^ m = 2, 3N ^ = 4, find the value of 9 ^ m + 1-2n
• 9. 3 × 9 ^ n × 27 ^ n-1 = 3 x 3 ^ 2n x 3 ^ (3n-3)
• 10. If the 2nth power of x = 3, find the value of the fourth power of (- 1 / 3 x to the 3nth power) / [the 2nth power of 4 (X & # 179;)]
• 11. Sn/Tn=3n+1/2n-1 RT please as soon as possible! Thank you~ If the sum of their first n terms is Sn / TN = 3N + 1 / 2N-1, then the ratio of the fifth term of these two sequences is? I forgot to enter the title when I was excited~
• 12. In the triangle ABC, if the angle a = 60 degrees and BC = 3, then the value range of AC + AB on both sides of the triangle ABC?
• 13. In the triangle ABC, if B = 2, angle B = 45 °, if the triangle has two solutions, find the value range of A The answer I got was 0 to 2 root 2, 2 to 2 root 2 The sine theorem of triangle is applied ~ (in triangle ABC, a / Sina = B / SINB = C / sinc)
• 14. In the triangle ABC, B = 4 and a = 2 are known. If the triangle has a solution, then the value range of ∠ A is given
• 15. It is known that in the triangle ABC, the angle B is equal to twice the angle c, and the proof of AC = AB + BD is given
• 16. In △ ABC, a = x, B = 2, B = 45 °, if the triangle has two solutions, then the value range of X is () A. x＞2B. x＜2C. 2＜x＜22D. 2＜C＜23
• 17. In the triangle ABC, if a = x, B = 2, angle B = 45 degrees, if there are two triangle ABC, then x range RT
• 18. If the angle a is 45 degrees and the length of the center line on the BC side is 3, the maximum area of the triangle ABC is obtained
• 19. In △ ABC, the corresponding sides of angles a, B and C are x, B and C respectively. If △ ABC with B = 2 and B = 45 ° has exactly two solutions, then the value range of X is () A. （2，+∞）B. （0，2）C. (2，22)D. (2，2)
• 20. In the known triangle ABC, BC = x, AC = 2, B = 45 degrees, if the triangle has two solutions, then the value range of X is?