An important theorem concerning derivatives is this: If a function f is differentiable at x = a, then f is continuous at x = a. The proof begins with the identity that for all And therefore, Since both sides are finite, the function is continuous at x = a. The converse of this theorem is…
Unit 2 contains topics rates of change, difference quotients, and the definition of the derivative (CED – 2019 p. 51 – 66). These topics account for about 10 – 12% of questions on the AB exam and 4 – 7% of the BC questions. Topics 2.1 – 2.4: Introducing and Defining the Derivative Topic 2.1:…
If you use your calculator or graphing program and zoom-in of the graph of a function (with equal zoom factors in both directions), the graph eventually looks like a line: the graph appears to be straight. This property is called Local Linearity. The slope of this line is the number called the derivative. (There are exceptions:…
Third in the graphing calculator series. In working up to the definition of the derivative you probably mention difference quotients. They are The forward difference quotient (FDQ): The backwards difference quotient (BDQ): , and The symmetric difference quotient (SDQ): Each of these is the slope of a (different) secant line and the limit of each as…
When determining the limit of an expression the first step is to substitute the value the independent variable approaches into the expression. If a real number results, you are all set; that number is the limit. When you do not get a real number often expression is one of the several indeterminate forms listed below:…
Our problem for today is to differentiate ax with the (usual) restrictions that a is a positive number and not equal to 1. The reasoning here is very different from that for finding other derivatives and therefore I hope you and your students find it interesting. The definition of derivative followed by a little algebra…
About this time of year you find someone, hopefully one of your students, asking, “If I’m finding where a function is increasing, is the interval open or closed?” Do you have an answer? This is a good time to teach some things about definitions and theorems. The place to start is to ask what it…
