A sequence cn is defined by the following recursion
cn+1=cn+cn−1 for every n≥1
and c0=1,c1=2.
-Let an=cn+1cn, for every n≥0 and prove that
an=1+1an−1 for every n≥1.
-Calculate the limit of the following sequence
c1c0,c2c1,c3c2,...,cn+1cn using the fact that this sequence is convergent
I tried close to everything to obtain the formula mentioned above but I did not succeed. What I obtained is an=1+cn−1cn which is obviously wrong. As for calculating the limit, I don't have a clue what is meant by 'using the fact that this sequence is convergent'. Could anyone please help me out? Thank you in advance.
Answer
Cn+1=Cn+Cn−1,An=Cn+1Cn
Substituting the first equation into the second equation you get: An=1+Cn−1Cn.
From the second equation we can write: Cn−1=CnAn−1.
Then we substitute this in our third equation and we get: An=1+(CnAn−1)/Cn.
is equal to 1+1An−1.
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