Final answer:
The understood domain of (x-4) / (x+1) is all real numbers except for x = -1.
Step-by-step explanation:
The understood domain of (x-4) / (x+1) is all real numbers except for the value of x that makes the denominator equal to zero. In this case, the denominator (x+1) equals zero when x = -1. Therefore, the understood domain of the expression is x ≠ -1.