Juan propped up a graham cracker in a shallow bowl. he then set up an electric fan to blow on the graham cracker at three different speeds. what is juan's independent variable in this experiment?

The independent variable is the changing fan speeds.
Independent variable are changed or controlled in experiments.

The answer is    (d) 7/2======we have    we also  have an integral      notice how function f splits up at x = 0. there's a left piece and a right pieceso we'll need to do the same thing with our integral: split it at x = 0we use a property of integrals that allows us to split up and sum:     notice that for the piecewise function f, the function has the equationf(x) = x when x  ≤ 0. so for the integral  , f(x) = x so it changes into      for the piecewise function f, the function has the equationf(x) = x+1  when x  > 0. for the integral  , we have    therefore, back to our splitted integral: