SOLUTION: The profit on t-shirts sold by a school is determined by the quadratic equation P=-x^2+30x+400 where x is the number of T-shirts sold at $10 each and P is the profit in dollars.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The profit on t-shirts sold by a school is determined by the quadratic equation P=-x^2+30x+400 where x is the number of T-shirts sold at $10 each and P is the profit in dollars.       Log On


   

Question 1172677: The profit on t-shirts sold by a school is determined by the quadratic equation P=-x^2+30x+400 where x is the number of T-shirts sold at $10 each and P is the profit in dollars.
a) determine the number of tshirts that must be sold to break even?
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

to determine the number of t-shirts that must be sold to break even,


solve the equation  -x^2 + 30x + 400 = 0 and use its positive root.


To solve it quickly, use factoring.