$\"\"$

\

The function $\"\"$ is continuous everywhere and $\"\"$ is a constant.

\

Need to verify $\"\"$ .

\

Consider $\"\"$ .

\

Let $\"\"$

\

Apply derivative on each side with respect to $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

If $\"\"$ , then $\"\"$ .

\

If $\"\"$ , then $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

\

Apply limits: $\"\"$ to $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

$\"\"$ .

\

$\"\"$

\

$\"\"$ .