$\"\"$

The Signup function is $\"\"$ .

Graph the function:

$\"\"$

Observe the graph:

As $\"\"$ tends to $\"\"$ from the left hand side, the function approaches to $\"\"$ .

$\"\"$ .

As $\"\"$ tends to $\"\"$ from the right hand side, the function approaches to $\"\"$ .

$\"\"$ .

Since the left hand limit and right hand limits are not equal, the limit does not exist.

$\"\"$ does not exist.

$\"\"$

$\"\"$ .

$\"\"$ does not exist.