`2^2+4^2+6^2+........... n` terms. find the sum of this series ?

If the sum of n terms of a series be a+bn+cn^(2) find the nth term and the nature of the series

Find the sum of 6 terms of the series 2+6+18+…..

Find the sum of first n terms and the sum of first 5 terms of the geometric series 1+(2)/(3)+

Find the nth term and the sum of n terms of the series 1.2.4+2.3.5+3.4.6+....

Find the nth term and hence the 20th term of series 2.4+4.6+6.8+…….. Also find the sum of its 20 terms.

Find the sum of n terms and sum to infinity of the following series : (1)/(2cdot4)+(1)/(4cdot6)+(1)/(6cdot8)+…

The nth term of a series is 3^(n)+2n; find the sum of first n terms of the series.

(2a^(2)-1)/(n),4a-(3)/(a),(6a^(2)-5)/(a)15. Find the sum of n terms of the series,36a- 5