Find the maximum of a polynomial trendline

[jondavis1987]

I would like a formula that automatically figures out what the maximum of poynomial trendline will be no matter what numbers i plug in there. I've seen a few explanations but they are all way above my head.

My X axis is A1:A4. Y axis B1:B4

X Axis Y Axis

9.7	105.8
11.9	111.5
14.5	113.3
16.8	110.2

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