00:01
All right, so for problem 14, right here we need to prove a given relation.
00:10
So again, we need to prove this by induction.
00:13
Now the basic step we consider here is when n is equal to 1.
00:21
Now f2 times f0 minus f1 squared is equal to 0 times 1.
00:32
Minus 1 squared, which is equal to negative 1 to the power of 1.
00:40
So it's negative 1.
00:43
Ok, so now we assume that when n equals k, we still have this relation that is fk plus 1 times fk minus fk squared, which is equal to negative 1 to the power of k.
01:06
Now we want to show that when n is equal to k plus 1, the relation still holds.
01:14
So on the left -hand side, we have fk plus 2 times fk minus fk plus 1 squared.
01:27
So if we take out fk, sorry, the first thing we do to do here is to rewrite, is to rewrite fk plus 2.
01:39
So we have fk plus 1 plus fk times fk and minus fk plus 1 squared.
01:57
Now if we expand the entire expression, so we have fk plus 1 times fk minus plus fk squared, minus fk plus 1 squared.
02:30
Now observe that we, for these two terms, they all have fk plus 1, so we can take out fk plus 1...