Find the `20^(t h)`term of the series
`2xx4+4xx6+6xx8+.....+n`terms.

Explanation

The given series is 2 × 4+4 × 6+ 6 × 8+....+n terms


`n` term=`a_n`
​
=2n×(2n+2)
=4`n^2`+4n


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