Revenue:$\displaystyle R(x) = 10x ^{2/3}$

Cost: $\displaystyle C(x) = 2x-9$

Finding the break-even point, i have the following:

R(x) = C (x)

R(x) - C (x) = 0

Therefore, the new function is$\displaystyle 10x^{2/3} - 2x + 9$

The derivative is $\displaystyle (20/3)*x^{-1/3} -2$

It is obvious to me, the answer is negative. However, you can have a negative answer for such question.

Please helps