$\"\"$

The function is $\"\"$ , $\"\"$ .

Differentiate with respect to $\"\"$ .

$\"\"$

Again differentiate with respect to $\"\"$ .

$\"\"$

Determine the values of $\"\"$ , at which $\"\"$ or $\"\"$ does not exist.

$\"\"$

Since $\"\"$ is always either less than or equal to $\"\"$ or greater than or equal to $\"\"$ , it never be equal to $\"\"$ .

Consider $\"\"$ .

So the concavity is depends on $\"\"$ .

Then $\"\"$ .

$\"\"$

The values of $\"\"$ is $\"\"$ in the given interval $\"\"$ . $\"\"$

Test for concavity in the intervals $\"\"$ and $\"\"$ .

\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

$\"\"$

The function is concave upward in $\"\"$ .

The function is concave downward in $\"\"$ .