Lecture 5 (Calculus)

The proof that Σ i³ equals (Σ i)² is streamlined by using the already-known fact that Σ from i = 1 to n of i equals:

1. A.n(n+1)(2n+1)/6
2. B.n²(n+1)²/4
3. C.n(n+1)/2
4. D.(n+1)²/2