Question 763065
P = -5*x^2 + 550*x - 5000

When P = 0

-5*x^2 + 550*x - 5000 = 0

Dividing by -5,

x^2 - 110x + 1000 = 0

(x - 100)*(x - 10) = 0

x = 100 or 10

Profit is 0 when the spend is 100000 dollars or 10000 dollars.

See the quadratic solution below as well

:)

*[invoke quadratic "x", 1, -110, 1000 ]