If a rational expression has a common factor (x + 1) that cancels in simplification, must x = -1 be excluded from the simplified expression's domain?

Only if (x + 1) also equals zero in the numerator at x = -1

Yes — if original denominator was zero at x = -1, that value remains excluded even after cancellation of (x + 1)

Only when working with rational numbers in decimals

No — cancellation removes any previous restrictions so x = -1 is allowed after simplifying