1.  (22 + 42 + 62 + ... + 202) = ?
A. 770
B. 1155
C. 1540
D. 385 x 385

Answer: Option C

Explanation:

(22 + 42 + 62 + ... + 202) = (1 x 2)2 + (2 x 2)2 + (2 x 3)2 + ... + (2 x 10)2

= (22 x 12) + (22 x 22) + (22 x 32) + ... + (22 x 102)

= 22 x [12 + 22 + 32 + ... + 102]

Ref: (12 + 22 + 32 + ... + n2) =1n(n + 1)(2n + 1)   
6

=4 x1x 10 x 11 x 21
6

= (4 x 5 x 77)

= 1540.