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How do I find the symmetry point for a graph based on a quadratic equation?

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marked as duplicate by Normal Human, Daniel W. Farlow, Joel Reyes Noche, Najib Idrissi, MPO Mar 31 at 8:35

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If you're familiar with the quadratic formula, take the mean of the two roots of the quadratic equation and simplify the resulting expression. –  Guess who it is. May 4 '11 at 13:47
If a quadratic function y = f(x) is meant, then J.M.'s suggestion is apt. A general quadratic equation will have at least one line of symmetry. Exactly one in the case of a parabola, even in general position, and exactly two in the case of a hyperbola. An ellipse will have two lines of symmetry as well, with only a circle, two parallel lines, and two intersecting lines (the degenerate cases) exhibiting one or more point symmetries. –  hardmath May 4 '11 at 14:22
Note that the graph of a quadratic equation has a line of symmetry, not a point of symmetry. –  Isaac May 4 '11 at 21:41

1 Answer 1

For an equation of the form $y= ax^2 + bx + c $ the axis of symmetry lies on the x-value $ \frac{-b}{2a}\ $.

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Aren't you missing a minus sign in there? –  Guess who it is. Nov 24 '11 at 5:00
Good catch! Next time, just go ahead and fix it though :) –  Adam Hammes Nov 25 '11 at 0:13