Following are the characteristics of my problem:
Objective function: two non-linear functions and one linear function
Decision variable: two integer variables ($X_1$ and $X_2$)
Constraint: three (two bounding constraint and one relationship constraint)
Constraint 1: $ 0 \le X_1 \le A_1$
Constraint 2: $ 0 \le X_2 \le A_2$
Constraint 3: $ X_1 + X_2 \le A_3$
$A_1,A_2$ and $A_3$ are positive constant numbers.
Problem type: non-convex
Solution required: Global optimum
Can we solve this problem using brand-and-bound method?