(For each given limit, if the numerical value of the limit exists, enter the answer as an integer or as a simplified fraction in lowest terms; if the limit doesn't exist, enter "DNE" in uppercase.) Let f (x) = 1x - 41 ( x + 2 ) (x-4) (x+7) . (a) Find lim f (x ) =? X-4+ (b) Find lim f ( x ) =? x-+4 A (c) Find lim f ( x ) =? x-4