Thus, $ f(x) = x^2 + 2x $, a quadratic, but consistent with the data. Despite being expected cubic, the data fits quadratic. Since the third differences are zero (first: 5,7,9; second: 2,2), third differences are zero, confirming degree â‰¤ 2.

Sat, 02 May 2026 22:48:21 +0000

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