In Example 4(a), change the t + 1 to t − 1 and then determine if t − 1 is a factor.

Data from Example 4(a)

We determine that t + 1 is a factor of f(t) = t³ + 2t² − 5t − 6 because f(−1) = 0, as we now show: f(−1) = (−1)³ + 2(−1)² − 5(−1) − 6 = −1 + 2 + 5 − 6 = 0.