The wolfram alpha links in the article and previous comments seem to be broken in that the parentheses in the mathematical expression are missing, meaning that the links present readers with the wrong answer. It was rather confusing for me for a bit. You might want to update the links to something like this:

S pdf: <http://www.wolframalpha.com/input/?i=integrate+3%2F2+*+%281+-+2*x+%2B+2*x^2%29+++from+0+to+1>
D pdf: <http://www.wolframalpha.com/input/?i=integrate+6+*+%28x+-+x^2%29+++from+0+to+1>