For the first equation, the denominator, also known as the divisor, is g. No denominator can be zero. Henceforth, this is the only limitation on the domain...
Please note that the parentheses, as opposed to brackets, indicate that the zero is NOT included.
For the second equation, let's look at the denominator/divisor...
k2 + k - 42
For the FOIL...
FIRST must be...(k)(k)=k2
OUTER and INNER must add-up to 1k or k.
Neither parenthetical equation can result in zero...
Parentheses indicate that neither -6 nor 7 are included.
AS PER STEVE'S COMMENT, I MADE THE CORRECTION HEREIN.