SOLUTION: Okay, this one has be banging my head on my desk. From June 2003 until April 2004 Blue airlines stock was worth approximately P=-4r^2+80t-360, where P denotes the price of the s

Algebra ->  Finance -> SOLUTION: Okay, this one has be banging my head on my desk. From June 2003 until April 2004 Blue airlines stock was worth approximately P=-4r^2+80t-360, where P denotes the price of the s      Log On


   

Question 223606: Okay, this one has be banging my head on my desk.
From June 2003 until April 2004 Blue airlines stock was worth approximately P=-4r^2+80t-360, where P denotes the price of the stock in dollars and to cooresponds to months, with t=1 cooresponding to January 2003.
During what months was the stock equal to $24
Answer by tutor_paul(519) About Me  (Show Source):
You can put this solution on YOUR website!
I assume you meant t^2 rather than r^2? If not let me know...
P=-4t%5E2%2B80t-360
P is the price, so set the equation equal to 24:
24=-4t%5E2%2B80t-360
Equate quadratic to zero:
-4t%5E2%2B80t-384=0
You can factor this:
%282t-24%29%28-2t%2B16%29=0
Equate each term to zero and solve for t:
2t-24=0
2t=24
highlight%28t=12%29
-2t%2B16=0
-2t=-16
highlight%28t=8%29
To get the actual months where the stock was $24, remember that January 2003 is 1. So you can see that the stock was at this price in August and December of 2003.
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Good Luck,
tutor_paul@yahoo.com