Here's the question you clicked on:
experimentX
is Wolf crazy? http://www.wolframalpha.com/input/?i=differentiate+abs%28x%29%2Fx+at+x%3D0
Indeed, another example of wolfram's craziness http://www.wolframalpha.com/input/?i=sec%283pi%2F2%29+-+tan%283pi%2F2%29
Indeed, this wolf is crazy.
here's one that's just another reason not to give DE's to the wolf http://www.wolframalpha.com/input/?i=4y%27%27%2B8y%27%2B2y%3Dcos%5E2x
this is crazy too. Maple does it simply.