Observe the graph of
.
is increases as the values of
increases.
Increasing and decreasing function :
\1. If
for all
in
, then
is decreasing on
.
2. If
for all
in
, then
is increasing on
.
So
as
is increasing on the interval
.
If the sign of the
is positive than
is also positive. \ \
Therefore
is also increases at the interval
.
and
.