# Help Algebra 2/Trigonometry Problem

#### daodude1987

I'm having trouble with proving this equation: x=-b\2a
I am not really familiar with this equation but my trigonometry teacher says it is something from Algebra 2. How can I prove why or how this equation works for finding the x-coordinate?

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#### iggybaseball

Taking into account that its almost midnight, i think i can scrap together an answer.

you are talking about using a specific equation:

ax^2 + bx + c ( quadratic)

however you use this equation:

f(x) = a(x-h)^2 + k (to put it into an equation that will make it easier to find the vertex of the equation)

h = -b/2a
k = c - ah^2 ( im almost positive this is right)

the vertex will equal (h,k) so if the vertex liex on the x axis u will have an x coordinate of the graph. hope that helps some

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