Let f(x) = (8x2) /(x-7) .
a) Find the interval(s) where f(x) is increasing.
b) Find the interval(s) where f(x) is decreasing.


a) (7, [infinity])
b) (-[infinity], 7)
c) (0, 7) and (7, [infinity])
d) (-[infinity], 0) and (7, [infinity])