Exploring the epsilondelta definition of limit
Move the slider to position point a.
Use the slider to choose a value of ε, and click the box to see the strip of yvalues that are less than ε units from L.
Use the slider to try to find a value of δ with the property that whenever x is less than δ units from a, then f(x) (the yvalue on the graph of f(x)) will be less than ε units from L. Click the box to see the strip of xvalues that are less than δ units from a. Look at the rectangle defined by the strip of xvalues and the strip of yvalues. If the graph of the function is green inside that rectangle, then you have chosen an appropriate value of δ.
Barbara D'Ambrosia, Created with GeoGebra
