Question

Find 3.7 + 5.10 + 7.13 + 9.16 + .... upto n terms.

Answer 1

Hey dear,

● Answer-

Sn = 2n^3 + 17/2 n^2 + 21/2 n

● Explaination-

nth term in given series is given by-

tn = (2n+1)(3n+4)

tn = 6n^2 + 11n + 4

To calculate sum of the series-

Sn = ∑ (6n^2 + 11n + 4)

Sn = 6 ∑n^2 + 11 ∑n + 4 ∑1

Sn = 6n(n+1)(2n+1)/6 + 11n(n+1)/2 + 4n

Sn = 2n^3 + 3n^2 + n + 11/2 n^2 + 11/2 n + 4n

Sn = 2n^3 + 17/2 n^2 + 21/2 n

Therefore, sum upto n terms is 2n^3 + 17/2 n^2 + 21/2 n .

Hope this help..

Answer 2

Answer:

answer is in the above attachment. please mark as brainliest