# Global maximum/ minimum of a function of more than one variable.

Please, can someone give me more information on how to check if points are local or global maximum/minimum. I am aware of the second derivative test of determining the local minimum/maximum. But how do I check for global min/max? An example to illustrate this would be very much appreciated. Thanks.

Thus, for $f:[a,b] \rightarrow \Bbb R$ differentiable, you should proceed as follows:
1. Calculate the zeros $x_1,x_2,x_3, ...$ of $f'(x)$
2. Calculate $f(x_1),f(x_2),f(x_3), ...$ as well as f(a)