$\"\"$

\

Let the function is $\"\"$ .

\

$\"\"$ and $\"\"$ for all $\"\"$ in the intervals $\"\"$ .

\

Consider $\"\"$ .

\

The value $\"\"$ .

\

The function is $\"\"$ .

\

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

\

$\"\"$

\

The least possible value of $\"\"$ .

\

$\"\"$

\

Consider $\"\"$ .

\

The value $\"\"$ .

\

The function is $\"\"$ .

\

Substitute $\"\"$ in the function of $\"\"$ .

\

$\"\"$

\

$\"\"$ .

\

$\"\"$ is greatest possible value of $\"\"$ .

\

$\"\"$

\

$\"\"$ is least possible value of $\"\"$ .

\

$\"\"$ is greatest possible value of $\"\"$ .