Home
Class 11
MATHS
Find the nth term of an A.P., the sum of...

Find the nth term of an A.P., the sum of whose first `n` terms is `3n^2+4n`

A

6n

B

6n+1

C

6n-1

D

none of these

Text Solution

Verified by Experts

The correct Answer is:
B
`S_n=3n^2+4n`
`S_1=3*1^2+4*1`
`=7=a_1`
`S_2=3*2^2+4*2`
`=12+8=20`
`S_2-S_1=a_2`
`20-S_1=a_2`
`a_2=13`
...
Promotional Banner

Topper's Solved these Questions

  • BINOMIAL THEOREM

    RD SHARMA|Exercise Solved Examples And Exercises|228 Videos

Similar Questions

Explore conceptually related problems

Find the rth term of an AP, the sum of whose first n terms is (3n^(2) +2n)

Find te rth term of an AP sum of whose first n terms is 2n+3n^(2).

(i) The sum of the first n terms of an AP is ((5n^(2))/(2) + (3n)/(2)) . Find the nth term and the 20th term of this AP. (ii) The sum of the first n terms of an AP is ((3n^(2))/(2) + (5n)/(2)). Find its nth term and the 25th term.

The nth term of an AP. Is (3+n)/(4) , then the sum of first 105 terms is

If the n^(th) term of an A.P.is (2n+1), find the sum of first n terms of the A.P.

The nth term of an A.P. is (5n-1). Find the sum of its 'n' terms.

if nth term of an AP is 3n+2 then find the sum n terms.

Find the sum of first n terms of the series whose nth term is 3n^(2)+5 .

RD SHARMA-ARITHMETIC PROGRESSIONS-Solved Examples And Exercises
  1. Which term of the sequence 20,19 1/4, 18 1/2, 17 3/4,... is the first ...

    Text Solution

    |

  2. Which term of the sequence 8-6i ,7-4i ,6-2i , is purely real ?

    Text Solution

    |

  3. Find the nth term of an A.P., the sum of whose first n terms is 3n^2+4...

    Text Solution

    |

  4. Show that the sequence defined by an=2n^2+1 is not an A.P.

    Text Solution

    |

  5. Show that the sequence loga ,log((a^2)/b),log((a^3)/(b^2)),log((a^4)/(...

    Text Solution

    |

  6. The nth term of a sequence is given by an=2n+7. Show that it is an A.P...

    Text Solution

    |

  7. Show that the sequence loga ,log(a b),log(a b^2),log(a b^3), is an A.P...

    Text Solution

    |

  8. Which term of the sequence 72, 70, 68, 66,... is 40?

    Text Solution

    |

  9. Show that the sequence is an A.P. if its nth term is linear expression...

    Text Solution

    |

  10. The nth term of a sequence is given by an=2n+7. find its 7th term.

    Text Solution

    |

  11. The product of three numbers in A.P. is 224, and the largest number is...

    Text Solution

    |

  12. The fourth power of common difference of an arithmetic progression wit...

    Text Solution

    |

  13. The sum of three terms of an A.P. is 21 and the product of the first ...

    Text Solution

    |

  14. The internal angles of quadrilateral are in A.P. and their common diff...

    Text Solution

    |

  15. Find the sum of all natural between 250 and 1000 which are exactly ...

    Text Solution

    |

  16. Find the sum of first 20 terms of an A.P., in which 3r d terms in 7 an...

    Text Solution

    |

  17. Find the number of terms in the series 20 ,19 1/3,18 2/3... the sum of...

    Text Solution

    |

  18. The sums of n terms of three arithmetical progressions are S1, S2and ...

    Text Solution

    |

  19. If in an A.P. the sum of m terms is equal of n and the sum of n ter...

    Text Solution

    |

  20. The first , second and the last terms of an A.P. are a ,b , c respect...

    Text Solution

    |