The number of tickets sold each day for an upcoming performance of Handel`s messiah is given by N(x)=-0.4x^2+8x+11, where x is the number of days since the concert was first announced. When will daily ticket sales peak, and how many tickets will be sold that day?

Question

anonymous · Answer

wow it has been a month since i have seen this one.

anonymous · Answer

peak is at 
$$x=-\frac{b}{2a}$$ with 
$$a=-0.4,b=8$$ you get 
$$x=-\frac{8}{2\times -.4}=\frac{8}{.8}=\frac{80}{8}=10$$ so peak sales are at day ten

anonymous · Answer

to find out how many tickets were sold, replace x by 10 and see

anonymous · Answer

replace x by 10? can you show me what that equation would look like?

anonymous · Answer

8200?

anonymous · Answer

sat?

anonymous · Answer

it would look like 
$$-0.4\times 10^2+8\times 10+11$$