David Little
Mathematics Department
Penn State University
Eberly College of Science
University Park, PA 16802
Office: 403 McAllister
Phone: (814) 865-3329
Fax: (814) 865-3735

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The Chain Rule

The following applet can be used to illustrate how the chain rule applies to the derivative of f(g(x)) at x=a. Simply enter the functions g(x) and f(x) and the value a. The applet automatically draws the graphs of g(x), f(x) and f(g(x)). The appropriate line tangent to the graph is drawn in red. For g(x), the tangent line goes through the point (a,g(a)), for f(x), the tangent line goes through the point (g(a),f(g(a))) and for f(g(x)), the tangent line goes through the point (a,f(g(a))).

The value of a can be changed by simply typing a new value, such as "1.2345", "pi/2", "sqrt(5)+cos(3)", etc. You may also change this value by using the up/down arrow keys or dragging the corresponding point left or right. To move the center of the graph, simply drag any point to a new location. To label the x-axis in radians (i.e. multiples of pi), click on the graph and press "control-r". To switch back, simply press "control-r" again.

Here is a list of functions that can be used with this applet.

© 2007 David P. Little
Download this applet for off-line viewing (includes source code). The above applet uses the Java Math Expression Parser (JEP) developed by Singular Systems