To minimize this don't you want x2 as small as possible? If so, then x2=x1^2. Then you're minimizing x^2-x, which is at x=1/2. If your bounds don't permit this, don't you just need to check the boundary values and x=1/2?
To minimize this don't you want x2 as small as possible? If so, then x2=x1^2. Then you're minimizing x^2-x, which is at x=1/2. If your bounds don't permit this, don't you just need to check the boundary values and x=1/2?