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Sequences and Series · Question 47

JEE Main 2025 (Online) 29th January Morning ShiftMCQMedium📈 Topic in 19% papers+4−1
1

The value of n ( k=1n k3 + 6k2 + 11k + 5(k+3)! ) is :

  1. 5/3
  2. 2
  3. 4/3
  4. 7/3

Answer

(1) 5/3

Solution

k3 + 6k2 + 11k + 5 = (k + 1)(k + 2)(k + 3) - 1

k3 + 6k2 + 11k + 5(k + 3)! = 1k! - 1(k + 3)!

Limit = k=1 1k! - k=1 1(k + 3)!

= (e - 1) - (e - 1 - 1 - 12 - 16 )

= 11! + 12! + 13! = 53

Answer: (1)

JEE Main 2025 (Online) 29th January Morning Shift

Keep practising — Sequences and Series

2

Let an be a sequence such that a0 = 0, a1 = 12 and 2an+2 = 5an+1 - 3an, n = 0, 1, 2, 3, . Then k=1100 ak is equal to

  1. 3a100 + 100
  2. 3a100 - 100
  3. 3a99 - 100
  4. 3a99 + 100
JEE Main 2025 (Online) 28th January Morning Shift
3

Let Tr be the rth term of an A.P. If for some m, Tm = 125, T25 = 120, and 20 r=125Tr = 13, then 5m r=m2mTr is equal to

  1. 98
  2. 126
  3. 112
  4. 142
JEE Main 2025 (Online) 28th January Morning Shift
4

For positive integers n, if 4an = (n2 + 5n + 6 ) and Sn = k=1n ( 1ak ), then the value of 507S2025 is :

  1. 540
  2. 675
  3. 1350
  4. 135
JEE Main 2025 (Online) 28th January Evening Shift
5

The interior angles of a polygon with n sides are in an A.P. with common difference 6 . If the largest interior angle of the polygon is 219 , then n is equal to .

JEE Main 2025 (Online) 28th January Evening Shift

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