proof by induction 5^n-1 is divisible by 4

Use mathematical induction to prove that the assertion is true for . is divisible by .

__basis__ then is divisible by .

__IH__ let and assume is divisible by .

__Induction Step__

Since is divisble by (by the induction hypothesis) then is also divisible by

Is this right?

What is wrong with the latex

Re: proof by induction 5^n-1 is divisible by 4

The induction step should have n = k+1

Re: proof by induction 5^n-1 is divisible by 4

Quote:

__IH__ let

and assume

is divisible by

.

If this is a proof by induction you need to go a step at a time, not prove it for all numbers at once.

I'd say this. "Assume . We want to show ."

Quote:

Since

is divisble by

(by the induction hypothesis) then

is also divisible by

Not quite, no. You have the formula wrong, and you need to show your work; how do you know 4 divides for certain?