Chapter 8 discusses five principles for making a graphic clear and understandable. One principle is that the graphic should have a purpose. What is another principle for making an effective graphic?

Use a while-end loop in a script file to calculate the sum of the first n terms of the series: summation sign on the top n bottom k=1 : )^k * k^2 +5k)/3^k show the script file and the two results of n = 10 and n = 20.