Given sum of the first n terms of an A.P. is 2n + 3n2. Another A.P. is formed with the same first term and double of the common difference, the sum of n terms of the new A.P. is:

Question

Given sum of the first n terms of an A.P. is 2n + 3n2. Another A.P. is formed with the same first term and double of the common difference, the sum of n terms of the new A.P. is: (A) n+4n2 (B) 6n2 - n (C) n2+4n (D) 3n+2n2

Tardigrade Admin · Accepted Answer

Given Sn = 2n + 3n2M Now, first term = 2 + 3 = 5 second term = 2(2) + 3(4) = 16 third term =2(3)+3 (9) = 33 Now, sum given in option only has the same first term and difference between 2nd and 1st term is double also.

Q. Given sum of the first $n$ terms of an $A . P .$ is $2 n + 3 n^{2}$ . Another $A . P .$ is formed with the same first term and double of the common difference, the sum of n terms of the new $A . P .$ is:

$n + 4 n^{2}$

$6 n^{2} - n$

$n^{2} + 4 n$

$3 n + 2 n^{2}$

Given $S_{n} = 2 n + 3 n^{2}$ M
Now, first term $= 2 + 3 = 5$
second term $= 2 (2) + 3 (4) = 16$
third term $= 2 (3) + 3 (9) = 33$
Now, sum given in option only has the same first term and difference between 2nd and 1st term is double also.

Q. Given sum of the first n terms of an A.P. is 2n+3n2. Another A.P. is formed with the same first term and double of the common difference, the sum of n terms of the new A.P. is:

n+4n2

6n2−n

n2+4n

3n+2n2