Give us the complete problem along with context. You have not even provided an equation. Maximize with respect to what?
Note to mathematicians: economists have their own conventions for math. For example, they frequently put the independent variable on the vertical axis. I suspect somewhere there is a definition of some function in this problem. Based on this fragment, we cannot even tell whether we are using univariate or multivariate calculus. The most common tool in many economic theorems are LaGrangians, which definitely means multivariate.