5. What is the first step in a proof by mathematical induction to show that "For all the positive intégers n, 12 + 22 + ... + n2 = n(n+1)(2+1) " is true? Assume the formula is true for n = k.
Show that the formula is true when n = 1.
Substitute k into the original formula,
Prove that the formula is true for the (k + 1) term.