Set Derive to Approximate Mode with 15 digits . (See next 4 slides.)
On the menu at the top of the Derive screen • click Options • then click ModeSettings
In the Mode field under Precision, click the arrow; click Approximate.
Now create a list of positive values of x that are approaching 0. I will use the following values: .1, .01, .001, .0001, .00001, .000001 Substitute these values, in turn, for x in the formula
Make sure the formula is highlighted on the Derive screen.
On the top toolbar (second line from the top) click the Sub(Substitute) button.
In the box that now appears, find the NewValue field and type .1. Then click Simplify. Derive now displays the answer.
Now click the formula on the Derive screen to highlight it again. Then repeat the previous substitute procedure for each of the remaining values of x in the list. You should see the following decimals.
Notice that these results seem to be approaching the number 0.25, that is,
Repeat the substitute procedure for a list of negative values of x that are approaching 0. I will use the following values: -.1, -.01, -.001, -.0001, -.00001, -.000001 You should obtain the following results:
Notice that these results also seem to be approaching the number 0.25, that is,
We see that the limit from the right and the limit from the left seem to be equal. So we conclude that