Question 182014
So it looks like your expression is [(x-8)/(x+5)]/[(x-9)/(x+4)].
x cannot be -5 because then (x-8)/(x+5) would be -13/0, so 0 would be the denominator, which make that fraction undefined.
x cannot be -4 because then (x-9)/(x+4) would be -13/0, so 0 would be the denominator, which make that fraction undefined.
x cannot be 9 because then [(x-8)/(x+5)]/[(x-9)/(x+4)] would be (1/14)/(0/13), which equals (1/14)/0, so 0 would be the denominator, which make that fraction undefined.