00:01
So we want to use induction to prove that 3 is a factor of n times n plus 1 times n minus 1 for every positive integer n.
00:08
So we'll start with the first step of induction, proving the case for n equals 1.
00:13
1 times 2 times 0 equals 0.
00:19
Oh, 3 is a factor of 0.
00:21
All positive integers are.
00:23
So that's that case proven.
00:25
Next we're going to write out the case k, which we assume to be true.
00:30
So k.
00:31
K plus.
00:32
1, k minus 1, biss has 3 as a factor, we assume so.
00:38
Now we're going to write out the 1 but we want to prove k plus 1.
00:42
So you have k plus 1, k plus 2, and k.
00:49
Okay, what i'm going to do is compare these two terms...