Question 60986
When your profit is zero, you receive as much money as you spent. So you want a profit greater than zero.
Profit > 0
Revenue - Cost > 0
50x - x^2 - 2x - 40 > 0
-x^2 + 48x - 40 > 0
*[invoke quadratic "x",-1,48,-40]
{{{(48 - sqrt(48^2 - 160))/2 < x < (48 + sqrt(48^2 - 160))/2}}}