Answer:
x = 1
Explanation:
Given
← factor numerator and denominator
=
← cancel (x - 4) on numerator/ denominator
=
The denominator of the rational expression cannot be zero as this would make it undefined. Equating the denominator to zero and solving gives the value that x cannot be.
x - 1 = 0 ⇒ x = 1 ← excluded value