



 
Megan, are you sure you don't have a typo in your question? I presume
This is a parabola opening downward. The vertical axis of the parabola is R (revenue) and the horizontal axis is p (price). Therefore if you want to know the maximum revenue (and the associated price to get that maximum revenue), you are asking to find the vertex of the parabola. The vertex of a parabola is the point (h, k) when you transform the equation into the standard parabolic form:
So transform your equation into this format (you will probably have to "complete the square" to do this) and you can just read off the value of k, which is the maximum revenue. Hope this helps,  


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