Final answer:
The flaw in the proof is that it assumes that if aⁿ = 1 for all nonnegative integers j with j ≤ k, then aᵏ⁺¹ = 1.
Step-by-step explanation:
The flaw in the proof is that it assumes that if aⁿ = 1 for all nonnegative integers j with j ≤ k, then aᵏ⁺¹ = 1. To demonstrate the flaw, we can consider a counterexample. Let's take a = 2 and k = 1. According to the assumption, 2¹ = 1. However, when we calculate aᵏ⁺¹ = 2² = 4, it does not equal 1.