Answer:
x = - 1
Step-by-step explanation:
Given
f(x) = x³ + x² + x + 1
If x = 1 is a factor then f(1) = 0
f(1) = 1³ + 1² + 1 + 1 = 4 ≠ 0 , thus x = 1 is not a zero
f(- 1) = (- 1)³ + (- 1)² + (- 1) + 1 = - 1 + 1 - 1 + 1 = 0
Thus x = - 1 is the only zero
