Home
Class 11
MATHS
If the sum of n terms of an AP is given ...

If the sum of `n` terms of an AP is given By `S_(n)=3n+2n^(2)` ,then the common difference of the AP is

A

3

B

2

C

6

D

4

Text Solution

Verified by Experts

The correct Answer is:
D
Given ` 1S_(n) = 3n+2n^(2)`
first term of the AP .
`T_(1) =3xx1+2(1)^(2)=3+2=5`
and `T_(1) ==s_(2)-S_(1)`
`=[3xx2+2xx(2)^(2)]-[3xx1+2xx(1)^(2) ]`
` =14-5=9`
`therefore ` Common difference `(d)=T_(2)-t_(1)=9-5=4`
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • SEQUENCE AND SERIES

    NCERT EXEMPLAR|Exercise Fillers|3 Videos

  • SEQUENCE AND SERIES

    NCERT EXEMPLAR|Exercise True / false|5 Videos

  • SEQUENCE AND SERIES

    NCERT EXEMPLAR|Exercise long answer type questions|4 Videos

  • RELATIONS AND FUNCTIONS

    NCERT EXEMPLAR|Exercise True /False|5 Videos

  • SETS

    NCERT EXEMPLAR|Exercise TRUE AND FALSE|6 Videos

Similar Questions

Explore conceptually related problems

If the sum of n terms of an AP is given by S_(n)=3n+2n^(2) then common difference of the AP is

If the sum of n terms of an AP is given by S_(n) = (2n^(2)+3n) then find its common differnece.

Knowledge Check

  • If the sum of n terms of an AP is given by S_n=n(2n-9) , then 10th term is

    A
    25
    B
    34
    C
    29
    D
    39

  • The sum of first n terms of an AP is (3n^(2) + 6n) . The common difference of the AP is

    A
    6
    B
    9
    C
    15
    D
    `-3`

  • Let s_(n) be the sum of the first n terms of an AP. If S_(2n)=3n+14n^(2) , then what is the common difference ?

    A
    A)5
    B
    B)6
    C
    C)7
    D
    D)9

    • Similar Questions

    Explore conceptually related problems

    If the sum of 'n' terms of an arithmetic progression is S_(n)=3n +2n^(2) then its common difference is :

    The sum of first n terms of an AP is given by S_(n)=2n^(2)+3n. Find the sixteenth term of the AP.

    If the sum of n terms of an A.P. is given by S_(n) =(3n^(2)+2n) , find its n^(th) term.

    The n^( th) term of an A.P. is a_(n)=3+2n , then the common difference is.

    If the sum of n terms of an A.P.is S_(n)=3n^(2)+5n. Write its common difference.

    Home
    Profile