Question

tell me the answer with proper steps

Answer 1

The formula for the sum of even squares is 2n (n+1) (2n+1) /3 where n= first n even natural numbers.
Since... youre asking until 40^2 that means that there are 20 even natural numbers which is for n.

Substitute for the formula..
40 (21) (41) / 3
= 40 x 7 x 41 = 11480

This took me quite a while, please mark brainliest, it would mean a lot to me :D