The function is
.
Consider
.
Derivative on each side by
.

Apply the power rule of derivative :
.

To examine the behavior of a function, equate the derivative to zero.
\
The
values are
and
.
The function is
.
The domain of the function is
.
There are four regions to examine the behavior of the function.
\First region
.
Consider a test point
in the region.
.
The derivative is negative, the function is decreasing over
.
Second region
.
Consider a test point
in the region.
.
The derivative is positive, the function is increasing over
.
Third region
.
Consider a test point
in the region.

The derivative is negative, the function is decreasing over
.
Fourth region
.
Consider a test point
in the region.

The derivative is positive, the function is increasing over
.
A monotonic function is increasing over
and
.
A monotonic function is decreasing over
and
.
Therefore the function is not strictly monotonic.
\The function is not strictly monotonic.