$\"\"$

Observe the graph of $\"\"$ .

$\"\"$ is decreases 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 decreasing on the interval $\"\"$ .

If the sign of the $\"\"$ is negative than $\"\"$ is also negative.

Therefore $\"\"$ is also decreases at the interval $\"\"$ .

$\"\"$

$\"\"$ and $\"\"$ .