Google Classroom
GeoGebraGeoGebra Classroom

5-A Extreme Values & Critical Points

Instructions

Use the input boxes below to define a function f(x) on an interval [a,b]. Use the checkboxes for a and b to exclude the endpoints from the domain of the function. Use the checkboxes to show/hide the critical points and local extrema in the interior of the interval (i.e., not at the endpoints). Use the "Trace y" button to trace points on the y-axis as you move the point c across the domain.

5-A Extreme Values & Critical Points

When we talk about extreme values of a function, we mean maximum or minimum values (without specifying which type). Global (Absolute) Extreme Values:
  • f has a global maximum at x=c if for all x in the domain of f.
  • f has a global minimum at x=c if for all x in the domain of f.
Local (Relative) Extreme Values:
  • f has a local maximum at x=c if for all x in an interval containing x = c.
  • f has a local minimum at x=c if for all x in an interval containing x = c.
Critical Points: The critical points of a function f are the points where either or does not exist. It turns out that all local extreme values must occur at a critical point. That is, the list of critical points is a list of potential extreme values. However, critical points do not always correspond to extreme values; so, the critical points must be tested to determine if there is an extreme value there.