Put the following statements into order to prove the summation formula P(n) = (∑i=0^n i^2 = n(n+1)(2n+1)/6) for all n ∈ ℕ. Put N next to the statements that should not be used.
1. By adding (n + 1)^2 to both sides of P(n), we get
2. Now suppose we have proved the statement P(n) for all n ∈ ℕ.
3. Now suppose we have proved the statement P(n) for some n ∈ ℕ.
4. The statement is true for n = 1 because in that case, both sides of the equation are 1.
5. ∑i=0^n i^2 + (n + 1)^2 = ∑i=0^(n+1) i^2 = n(n+1)(2n+1)/6 + (n + 1)^2
6. The statement is true for n = 1 because in that case, both sides of the equation are 0.
7. ∑i=0^n i^2 + n + 1 = ∑i=0^(n+1) i^2 = n(n+1)(2n+1)/6 + n + 1
8. By adding n + 1 to both sides of P(n), we get
9. Thus, we have proved the statement P(n + 1) = (∑i=0^(n+1) i^2 = (n+1)(n+2)(2n+3)/6)
10. We simplify the right side: n(n+1)(2n+1)/6 + (n + 1)^2 = (n + 1)(n(2n+1)/6 + n + 1) = (n+1)(n+2)(2n+3)/6
11. We simplify the right side: n(n+1)(2n+1)/6 + (n + 1) = (n + 1)(n(2n+1)/6 + 1) = (n+1)(n+2)(2n+3)/6