Determine which of the following polynomials has (x + 1) a factor: x³ + x² + x + 1

(i) Let p(x) = x³ + x² + x + l
Putting x + l = 0, we get, x = -1
Using remainder theorem, when p(x) = x³ + x² + x + l is divided by x + 1, remainder is given by p(-1)
= (-1)³ + (-1)² + (-1) + 1
= -1 + 1 – 1 + 1 = 0
Since, remainder p(-1) = 0, hence x + 1 is a factor of x³ + x² + x + l.