1. 3.2 Derivatives Great Sand Dunes National Monument, Colorado Greg Kelly, Hanford High School, Richland, WashingtonPhoto by Vickie Kelly, 2003

2. We write: “The derivative of f with respect to x is …” There are many ways to write the derivative of

3. “f prime x”or “the derivative of f with respect to x” “y prime” “dee why dee ecks” or “the derivative of y with respect to x” “dee eff dee ecks” or “the derivative of f with respect to x” “dee dee ecks uv eff uv ecks”or “the derivative of f of x”

4. dx does not mean d times x ! dy does not mean d times y !

5. does not mean ! (except when it is convenient to think of it as division.) does not mean ! (except when it is convenient to think of it as division.)

6. (except when it is convenient to treat it that way.) does not mean times !

7. In the future, all will become clear.

8. The derivative is the slope of the original function. The derivative is defined at the end points of a function on a closed interval.

11. A function is differentiable if it has a derivative everywhere in its domain. It must be continuous and smooth. Functions on closed intervals must have one-sided derivatives defined at the end points. 

12. To be differentiable, a function must be continuous and smooth. Derivatives will fail to exist at: cornercusp vertical tangent discontinuity

13. Most of the functions we study in calculus will be differentiable. If a function is differentiable, then it is continuous. Note!! Just because a function is continuous does not mean that it is differentiable!!!

14. Example Show that the following function is continuous but not differentiable at x = 1. Sketch the graph of f.

15. Derivatives on the TI-89: You must be able to calculate derivatives with the calculator and without. Today you will be using your calculator, but be sure to do them by hand when called for. Remember that half the test is no calculator.

16. Example: Find at x = 2. d ( x ^ 3, x ) ENTER returns This is the derivative symbol, which is. 8 2nd It is not a lower case letter “d”. Use the up arrow key to highlight and press. ENTER returns or use: ENTER

17. Warning: The calculator may return an incorrect value if you evaluate a derivative at a point where the function is not differentiable. Examples: returns

18. Graphing Derivatives Graph:What does the graph look like? This looks like: Use your calculator to evaluate: The derivative of is only defined for, even though the calculator graphs negative values of x.