SOLUTION: Would someone show me step by step how to figure this problem. Please. Thank You. The profit on a watch is given by P=x^2-13x-80, where x is the number of watches sold per day.

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Would someone show me step by step how to figure this problem. Please. Thank You. The profit on a watch is given by P=x^2-13x-80, where x is the number of watches sold per day.       Log On


   

Question 83917: Would someone show me step by step how to figure this problem. Please. Thank You.
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 jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
If there was a $50 loss, then P=-50

-50=x%5E2-13x-80 Plug in P=-50. Now lets solve for x

0=x%5E2-13x-80%2B50 Add 50 to both sides

0=x%5E2-13x-30 Combine like terms

0=%28x%2B2%29%28x-15%29 Factor the expression

x%2B2=0 or x-15=0 Set each factor equal to zero

x=-2 or x=15 Solve for x in each case

Since you cannot sell -2 watches, the number of watches sold was 15