[Math] How to find an explicit formula for a sequence defined recursively.

real-analysissequences-and-series

Consider the sequence defined recursively by $x_1$=$\sqrt2$ and where $x_n$=$\sqrt2$ + $x_n$$_-$$_1$.

Find a explicit formula for the $n^t$$^h$ term.

I considered using the general equation to find an explicit formula for any term in an arithmetic sequence. a$_n$ = a$_1$ + $d(n-1)$, but I came to no conclusion helping my argument.

Am I using the correct method?

Best Answer

Here is an approach.

$$ x_{n+1}-x_{n}=\sqrt{2} \implies \sum_{i=0}^{n-1}( x_{i+1}-x_{i}) = \sqrt{2}\sum_{i=0}^{n-1}1 $$

$$ \implies x_n-x_0=\sqrt{2} n .$$

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