### Home > CALC > Chapter 6 > Lesson 6.1.4 > Problem 6-53

6-53.

Be careful! Evaluating this limit as *n* → 0 leads us to trouble:

Refer to part (a).

That means we do not know if the limit is finite (because the 0's 'cancel out') or infinite (because there is a 0 in the denominator).

We can evaluate an indeterminate limit if that limit happens to be a definition of the derivative.

Sure enough, part (a) is Ana's Definition of the Derivative:

Since *n* → 0, notice that *a* = 0. So we can rewrite the limit as:

So, we just need to find *f* '(*x*) at *x* = 0 and we have evaluated the limit.

Now evaluate that derivative at *x* = 0: