Answer:
x=4 and x=-4
Explanation:
We assume you intend ...
y = (x^2 +5x +6)/(x^2 -16)
There will generally be points of discontinuity where the denominator is zero. Sometimes a denominator factor will be cancelled by a numerator factor, but the "hole" remains and there is still a discontinuity there.
Here, the denominator factors as the difference of squares:
x^2 -16 = (x -4)(x +4)
There will be discontinuities where these factors are zero, at x=4 and x=-4.