Power Point Links

I uploaded the PPTs to Google Docs and got the links to share with you.  However, I just tested it and no go - the slides are all messed up.  You guys have been taking notes since starting the PPT's - study your notes and you'll be fine.  Sorry about that.  I'll work on ways to do this for the future.

Introducing the Derivative

Before watching this video (which is a little dry, I warn you), you should keep in mind the ultimate "prize" --

                THE SLOPE OF THE TANGENT LINE

Why?  Because tangent lines tell us a lot about curves, even complicated ones.  On a piece of paper, draw a curve that goes up and comes down a few times.  Choose a bunch of points on the curve and draw the tangent lines at those points?  What do you notice?

1.  When the curve seems to be going uphill (looking from left to right), what do you notice about the tangent line?  Positive or negative slope?

2.  Likewise, as the curve goes downhill, the slopes will have the same sign.  Do all downhill slopes have the same value?

3.  At the points where the curve turns around, what are the slopes of the tangent lines?

You should notice that the tangent lines are useful in describing the curve.  That's what mathematicians are all about... finding numerical ways to describe behavior, in this case, function behavior.  Instead of saying that the curve seems to be "going uphill" sharply at a certain point, we can say that the slope of the tangent line is "positive 4" or "positive 20" or whatever.  This tells us that, yes, the curve is going uphill and it also tells us exactly how steep it is.  Efficient, huh?!

Watch the video link below, close to 10 minutes long.  At about 4 minutes into the video, the teacher will bring up an example of an object in free fall.  Answer these questions for this week's post:

a.  Why does the speed of the object differ on time intervals (2, 3) and (3, 4)?

b.  What rudimentary method does he use to find the slope of the tangent line?  Why is this inadequate?

c.  In BC times (before calculus), you needed two points to find a slope.  First, the man uses 3 and 3.1 as the two x-values; then, he uses 3 and 3.01.  What concept allows us to use smaller than 3.000000001 as an x-value?

So, here's the very important point:  the DERIVATIVE of a function = SLOPE OF THE TANGENT LINE.

 
Well, here's the link.  Get some popcorn:   Instantaneous Rate of Change

Limits of Rational Functions

After watching the 5 minute video linked below, answer the following questions:

1.  The first function had an error message in the table at x = 0.  Why?

2.  Does this problem matter when "eye-balling" the limit?

3.  If you were using your calculator to assist you in drawing a graph, what would you put on your graph that is not on the calculator screen?

4.  The second function had error messages at x=1 and at x= -1.  What is the difference between them?

5.  If you're approaching a hole in the graph of a rational function, the limit still exists.  How about if you're approaching a vertical asymptote?


Rational Functions - Use a calculator??

More on Limits

Last week, I posted about the idea of a limit.  Your posts were heading in the right direction but "not quite there."  I found out that you haven't been introduced to this concept yet and it's very important that you understand limits.

We'll talk about limits in class but I found an 8-minute video on Teacher Tube that I'd like you to watch.  It's well-made and easy to understand.

A Good Look at Limits

 Remember these three things:

• The word limit (or lim - the abbreviation) must be followed by a function. 
• Beneath the word limit, you will find the part of the graph you're supposed to focus on.  It will be described by an x-value. 
• The answer to limit problems, if the limit exists, is always a y-value.  It describes the intended destination of the function.  

For your post this week, after watching the video, I'd like you to think about the function below:

lim  (x^3 + x - 1)
x---> 4

Evaluate this limit.  What would happen to the limit if I restricted the domain to [-4, 4]?

Jake's function last week was y = sqrt(x)?  Where, in its domain, does the limit not exist and why?

Have a good weekend... see you Tuesday.