Am I doing this function question correctly?

Question

f(x) = x+4 / x^2 + x - 56

 

Find all values of x that are not in the domain of f. If there is more than one value, separate them with commas.

 

I factored the quadratic into (x - 7) ( x + 8)

 

So does that mean my answer, for each value of x that is not in the domain, would be -4, 7, and -8?

Answer 1

Almost.  It's OK for f(x) to equal zero, so -4 is in the domain of f(x).  It's not OK, however, to divide by zero; so 7 and -8 are not in the domain of f(x).  The answer is -8, 7.

 

Good job on the factoring, BTW.