Find the critical points and the intervals on which the function is increasing or decreasing. Use the First Derivative Test to determine whether the critical point is a local min or max (or neither).
When f'(x) > 0 for all x on a defined open interval, then f is zfi1I3d4PvPpiEdCcEYd3mwzJ2Jn7ZmnBM/VedVTNWNmHo9/C0wmIKERkIE= on that interval.
When f'(x) < 0 for all x on a defined open interval, then f is lb1yDssyhRoDeV34+lBpA1Q20o6SPKA4XGI914rrm6KYpxdQB7vRY8wbTYQ= on that interval.
In order to determine intervals of increase and decrease, we need the critical points of f(x).
A number c in the domain of f is called a critical point if either f'(c) = 1Wh3cvJ2xF4= or where f'(c)risoekzpYAAgRXECVAcsXWXnXFT9zJ4gDoyL7g==.
Find f'(x).
where b = nc1ItEz0kR4= and c = iSba6t70dtA=.
Solve f'(x) = 0 to find any critical points, c.
The critical points are
c =VuqerCroNnN8kEVC, JRTGa0xCnPWOxQpY.
(Enter the smaller value first.)
Use the two critical points to divide the real line into three intervals.
(-∞,$pmax),($pmax,$pmin),($pmin,∞)
To determine where f(x) is increasing or decreasing, pick an x-value in each interval, and identify the sign of f'(x).
Let's pick x1 = $x1 in the first interval, x2 = $pmax in the second interval, and x3 = 0 in the third interval. Fill in the table below with the appropriate sign.
Interval | x-value | Sign of f'(x) |
---|---|---|
(-∞,$pmin) | $x1 | brSjF5lOKMQ= |
($pmin,$pmax) | $pmax | 097XeLvBC5c= |
($pmax,∞) | 0 | brSjF5lOKMQ= |
Thus, f is increasing and decreasing on the following interval(s).
H9aHpkMf02hQ4OjDixAlXGOJkScAubK24CWmXA== (-∞,$pmin) ($pmax,∞)
p2CFj3VtDXt2cxcALfSQpMJFT8s4YoKX6KzyhQ== ($pmax,$pmin)
The First Derivative Test for critical points states that for any critical point x = c:
If f'(x) changes sign from + to − at x = c, then f(c) is a local MLrjsAZLmRw2xfA/t8djnqWlqT8=.
If f'(x) changes sign from − to + at x = c, then f(c) is a local cCmYpIf3+uu6kk3FVOz/JXh4+jw=.
Thus, f has a local minimum at c = VuqerCroNnN8kEVC and a local minimum at c = JRTGa0xCnPWOxQpY.