$\"\"$

The function is $\"\"$ .

Rewrite the above function as $\"\"$ .

The above function at $\"\"$ is

$\"\"$

The value of $\"\"$ and $\"\"$ are same.

Thus, Use $\"\"$ to approximate the function $\"\"$ near $\"\"$ .

$\"\"$

Use $\"\"$ to approximate the function $\"\"$ near $\"\"$ .