SOLUTION: Tickets sold = -0.2x^2+12x+11 x=1 is the day tickets go on sale. Use the quadratic equation to determine the last day tickets will be sold. I replaced x with 1 in the equation abo

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Tickets sold = -0.2x^2+12x+11 x=1 is the day tickets go on sale. Use the quadratic equation to determine the last day tickets will be sold. I replaced x with 1 in the equation abo      Log On


   

Question 460257: Tickets sold = -0.2x^2+12x+11
x=1 is the day tickets go on sale. Use the quadratic equation to determine the last day tickets will be sold. I replaced x with 1 in the equation above to determine 22.8 tickets were sold on day one, but I'm not sure that is correct. How do I find out the last day tickets were sold? Can you show the work so I can understand how to find the answers? Thanks so much. =)
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Tickets sold = -0.2x^2+12x+11
x=1 is the day tickets go on sale.
Use the quadratic equation to determine the last day tickets will be sold.
I replaced x with 1 in the equation above to determine 22.8 tickets were sold
on day one, but I'm not sure that is correct.
:
That is correct, but since you can't have a fraction of ticket is would be 23 ticket on day 1
:
How do I find out the last day tickets were sold?
:
That would be when the tickets sold = 0, this is quadratic equation that will
peak and then return thru 0
:
-0.2x^2 + 12x + 11 = 0
you will have to use the quadratic formula to find x
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In this equation; a=-.2, b=12, c=11
x+=+%28-12+%2B-+sqrt%2812%5E2-4%2A-.2%2A11+%29%29%2F%282%2A-.2%29+
:
x+=+%28-12+%2B-+sqrt%28144-%28-8.8%29%29%29%2F%28-.4%29+
x+=+%28-12+%2B-+sqrt%28144%2B8.8%29%29%2F%28-.4%29+
x+=+%28-12+%2B-+sqrt%28152.8%29%29%2F%28-.4%29+
Two solutions
x+=+%28-12+%2B+12.33%29%2F%28-.4%29+
x = .33%2F%28-.4%29
x = -.825, obviously this is not our solution
and
x+=+%28-12+-+12.33%29%2F%28-.4%29+
x = %28-24.33%29%2F%28-.4%29
x = +60.825 ~ 61 days for 0 tickets to be sold
:
You can substitute 60.825 for x in the original equation and prove it to yourself
:
Did this make sense to you?