00:01
Okay, so here we want to express the recurrence relation in terms of its backwards differences, right? and so we know that the backwards difference of a sequence is going to be equal to that sequence a sub -n minus a sequence a sub -n minus one.
00:25
And so i'm going to go ahead and use this to determine the second difference, which would be expressed.
00:34
As the first difference of a n minus the first backwards difference of a sub n minus one.
00:46
So this is going to be equal to, just using the formula above it, a n minus a n minus 1 minus a n minus 1 minus a n minus 1 minus a sub n minus 2.
01:07
Okay, so this ends up equaling a sub n minus 2, a sub n minus 1 minus a sub n minus 2.
01:31
Okay, so our goal is going to be to express an equaling a n minus 1 plus a n minus 2 in terms of their backwards differences.
01:48
So we're going to go ahead and start way.
01:53
From the derivation that we did here, where we have this second backwards difference being equal to this.
01:59
We're just going to rewrite that...