To find the global extrema, check the local extrema and the limit of the function approaching the bounds.
We have a local extremum at . What's f(x) of the point?
Now check the bounds.
We have 3 possible values to be the global extrema.
-- (the local extrema, x=1)
-- (left bound)
-- (right bound)
The greatest of these values, is the global maximum, and the least, is the global minimum.