Question

The sum of cubes of  the first n natural numbers is given by _________

(a) {n(n+1)/2}^2

(b) {n(n-1)/2}^2

(c) {n2(n+1)/2}^2

(d) None of the mentioned

I had been asked this question during an interview.

This key question is from Special Sequences topic in chapter Basic Structures: Sets, Functions, Sequences, Sums and Matrices of Discrete Mathematics

Answer 1

Correct choice is (a) {n(n+1)/2}^2

For explanation I would say: 1^3 + 2^3 + 3^3 + 4^3 +……+ n^3 = {n(n+1)/2}^2.