SOLUTION: The profit on a watch is given by P = x^2 – 13x – 80, where x is the number of watches sold per day. How many watches were sold on a day when there was a $50 loss?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: The profit on a watch is given by P = x^2 – 13x – 80, where x is the number of watches sold per day. How many watches were sold on a day when there was a $50 loss?      Log On


   



Question 104761: The profit on a watch is given by P = x^2 – 13x – 80, where x is the number of
watches sold per day. How many watches were sold on a day when there was a
$50 loss?

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
For a $50 loss, then the profit was -50.
Find x such that P(x)=-50.
P%28x%29=-50
x%5E2-13x-80=-50
x%5E2-13x-30=0
%28x-15%29%28x%2B2%29=0
Two solutions
x=15 and x=-2.
Selling (-2) watches doesn't make sense, so your only answer is 15 watches sold.
Check your answer.
x%5E2-13x-80=-50
%2815%29%5E2-13%2815%29-80=-50
225-195-80=-50
-50=-50
Good answer.