The number of tickets sold for a concert event can be modeled by y= -x^2/8+x+1, where x is the time in hours since the tickets have begun to sell, and y is the number of tickets sold per hour. For how long will tickets be sold?

A. 6.71 hours C. 8.90 hours
B. 8.12 hours D. 11.05 hours

Question

The number of tickets sold for a concert event can be modeled by y= -x^2/8+x+1, where x is the time in hours since the tickets have begun to sell, and y is the number of tickets sold per hour. For how long will tickets be sold? 

A. 6.71 hours 					C. 8.90 hours
B. 8.12 hours 					D. 11.05 hours

tkhunny · Answer

How long does y stay positive?

anonymous · Answer

Wait is that answer D?

tkhunny · Answer

You didn't answer my question.  No guessing.  Prove it!

tkhunny · Answer

Come on!  You can do it!  There is a reason why you studied Quadratic Equations until your eyes were falling out.  Now is the time!

-x^2/8+x+1 = 0 -- Solve for x.