Question

How do you use a graphing calculator to find the limit of `x^2-5x` as x approaches -1?

Answer 1

`lim_(x rarr -1) x^2-5x =6`

Explanation:

Use the calculator to plot the function and look at what happens near and at `x=-1`.

In this case as the function is a polynomial, it is "well behaved", and the limit is found by substituting `x=-1` to give:

`lim_(x rarr -1) x^2-5x = 1+5 = 6`

As can be confirmed by the graph:
graph{x^2-5x [-2, 6, -4, 8]}