Find the sum of the series 22 + 42 + 62 + 82 +... 20 terms.
Given series 22 + 42 + 62 + 82 +...
Above given series is sum of the square of first 20 even numbers.
Nth term of the series
tn = (2n)2 = 4n2
Sum of the n terms
Sn=∑ni=1tn=4∑ni=1n2
= 4.n(n+1)(2n+1)6 : substitute n = 20
= 4×20×21×416 = 11480