This applet graphs two functions, [math]f(x) = 2^x[/math] and [math]h(x) = log_2 x[/math]. Since these two functions have the same base, they are strongly related. As you move the slider marked [math]v[/math] you can see the two points on the graph move. Notice that the two points are always related by the fact that if you're looking at [math]\left( v, h(v) \right)[/math] on [math]h(x)[/math], then the point on [math]f(x)[/math] is the reverse, or [math]\left( h(v) , v \right)[/math]. The slider can be moved from -5 to 3 in 0.1 increments.
