Question 625213
I need help, I am stuck on this word problem from Quadratic Equations: 
The number of tickets sold each day for an upcoming performance of Handel's Messiah is given by N(x)=-0.5x^2+11x+15, where x is the number of days since teh concert was first announced. When will the daily ticket sales peak and how many tickets will be sold that day?
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N(x)=-0.5x^2+11x+15
This equation is that of a parabola that opens downwards (negative lead coefficient)
Parabola has a maximum
Its form of equation:y= -A(x-h)^2+k, (h,k)=(x,y) coordinates of the vertex.
N(x)=-0.5x^2+11x+15
to find vertex, complete the square:
N(x)=-0.5(x^2-22x+121)+15+60.5
N(x)=-0.5(x-11)^2+75.5
vertex: (11,75.5)
When daily ticket sales will peak: 11 days since concert was announced
Tickets sold that day=75