Question 652251
"Finding the domain" is a fancy pants way of saying "find where the denuminator is not zero"

(x + 7)/(x^2 - 36) factors to:

(x + 7)/(x - 6)(x + 6)

If x = 6, the denominator would equal zero (6 - 6)(6 + 6) = (0)(12) = 0.  So, 6 is excluded.  Same for -6.

Domain is "all Real numbers except 6 and -6"

Now, if one of those (  ) in the denominator cancelled with the (x + 7) in the numerator, we could cancel that parenthesis and have only one exception to the domain.  Example: (x + 6)/(x + 6)(x - 6).  The (x + 6)s cancel so that the domain would be "all Reals except 6 (only)."