SOLUTION: For a chemical reaction, temperature is a function of time. For Denver Poweroxide this function is T = -t^2 + 7t + 8 (T is degrees Fahrenheit and t is seconds). How long will it

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: For a chemical reaction, temperature is a function of time. For Denver Poweroxide this function is T = -t^2 + 7t + 8 (T is degrees Fahrenheit and t is seconds). How long will it       Log On


   

Question 78037: For a chemical reaction, temperature is a function of time. For Denver Poweroxide this function is T = -t^2 + 7t + 8 (T is degrees Fahrenheit and t is seconds). How long will it take for the temperature to reach zero? Solve by graphing.
I got: 1 second. Is this correct?
Thanks~
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
T = -t^2 + 7t + 8
T=-0
-t^2+2t+8=0
Multiply thru by -1 to get:
t^2-2t-8=0
Factor to get:
(t-4)(t+2)=0
t=4 seconds is the only positive answer.
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Cheers,
Stan H.