Let f(x)= (x+3)(x-3)/5x+8

a) Find all values of x such that f(x)=0 or f is discontinuous at x (1.e. all of the numbers that you would mark on a sign chart for f). Enter your answers as a comma-separated list.

x=

b) Find the intervals on which f is positive and the intervals on which is negative. Express your answers in interval notation.

f is positive on ____.
f is negative on____.


Be sure that you can fully justify your answer with a sign chart and associated computations and that you can do this problem using only the technology that will be allowed on tests.