C-13-Q066mediumsingle_mcq13+23+33+⋯+n3=?1^{3} + 2^{3} + 3^{3} + \cdots + n^{3} = ?13+23+33+⋯+n3=?an(n+1)(2n+1)6\dfrac{n(n+1)(2n+1)}{6}6n(n+1)(2n+1)b