Prove that 5^(2n - 1) is divisible by 8

Step-by-step explanation:

Prove that 52n − 1 is divisible by 8 for all n ∈ N.

Solution

To prove by induction, we must

1. Show it is true for n = 1

2. Assume true for n and prove it is true for n + 1.

Let P(n) be the statement 52n − 1 is divisible by 8.

When n = 1, 52 − 1 = 24, which is divisible by 8.

This proves P(1).

Suppose that P(n) is true, i.e., 52n − 1 is divisible by 8.

Then 52(n+1) − 1 = 52

· 5

2n − 1 = 52

(52n − 1) + (52 − 1).

Note that 52n −1 is divisible by 8 using P(n) and also 52 −1 = 24 is divisible

by 8. Thus we have proved that P(n + 1) is true.

We conclude that P(n) is true for all n ∈ N.

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step-by-step explanation:

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right