I took a shot anyway. First I used a linest trick mentioned here:
http://stackoverflow.com/questions/1...ssion-in-excel. To get the coordinates of the quadratic.
The X-Values are in Cells A1:A5 (I gave this a name My_X)
The Y-Values are in Cells B1:B5 (I gave this a name My_Y)
The Coefficients are in cells E2:G2. This is the linest equation entered as an array formula.
Basic Calculus. The first derivate of Ax^2 + Bx + C is 2Ax +B. Where this is Zero is the maximum or minimum of the quadratic. Solving for Zero gives =-B/2A. That's the formula in Cell F4. Cell F5 contains the Y value at that point.
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