∫1/(x^(3/2)) = -2/sqrt(x) ???

im trying to figure out the rule here. its poping up a few times. these 2 questions especially:

Wolfram|Alpha

(click on "show steps" and look at step 3)

or here

Wolfram|Alpha

(sort of the same question really).

whats going on there? can someone show the working out to me for how we end up with the answer?