5. Use polynomial fitting to find a closed formula for the sequence ($a_n)_{n\ge1}$: 4, 11, 20, 31, 44, .... \text{Solution.} $a_n = n^2 + 4n - 1.$
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.. Notice that the sequence seems to be increasing by increasing amounts. This suggests that the underlying formula might be a polynomial. Let's denote the nth term of the sequence as \(a_n\). Step 2: To find a polynomial that fits the sequence, let's start by Show more…
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