MathItems
Theorem T43
∑
k
=
1
n
k
3
=
(
∑
k
=
1
n
k
)
2
\sum_{k=1}^n k^3 = \left( \sum_{k=1}^n k \right)^2
k
=
1
∑
n
k
3
=
(
k
=
1
∑
n
k
)
2