In Rosen's book Discrete Mathematics and Its Applications, 8th Edition it is mentioned that:
You may be surprised that mathematical induction and strong induction are equivalent. That is, each can be shown to be a valid proof technique assuming that the other is valid.
One of the examples given for strong induction in the book is the following:
Suppose we can reach the first and second rungs of an infinite ladder, and we know that if we can reach a rung, then we can reach two rungs higher … prove that we can reach every rung using strong induction
If the two proof techniques are "equivalent", how can I prove the above example using mathematical induction (as opposed to strong induction)?