12 + 22 + 32 + 42 + ........... + 202 = কত?
A 2560
B 2740
C 2320
D 2870
Solution
Correct Answer: Option D
আমরা জানি,
12 + 22 + 32 + 42 + ........... + n2 = (1/6){n(n+1)(2n + 1)}
12 + 22 + 32 + 42 + ........... + 202 = (1/6){20(20+1)(2×20 + 1)}
= (20×21×41)/6
= 2870