Find the 20th term and the sum of 20 terms of the series: `2xx4+4xx6+6xx8+..........`

Explanation

Given series is `2 xx 4+4 xx 6+6 xx 8+...+n` terms


`nth` term=`2n xx (2n+2)=4n^2+4n`


`a_20=4(20)^2+4(20)^2=1600+80=1680`


Thus, the `20th` term of the series is `1680`.