If $(x+1)$ is factor of $x^3 + kx^2 - 3x + k + 2$, then $k$ is equal to:
Step-by-Step Solution
Key Concept: Factor theorem
Step 1: Understand the factor theorem.
If $(x+1)$ is a factor of the polynomial $p(x) = x^3 + kx^2 - 3x + k + 2$, then by the Factor Theorem, $x = -1$ must be a root of the polynomial. This means $p(-1) = 0$.
Step 2: Substitute $x = -1$ into the polynomial.
We substitute $x = -1$ into the expression:
$$p(-1) = (-1)^3 + k(-1)^2 - 3(-1) + k + 2$$
Step 3: Simplify each term.
Let us evaluate each term:
- $(-1)^3 = -1$
- $k(-1)^2 = k(1) = k$
- $-3(-1) = 3$
- The constant terms are $k + 2$
So we have:
$$p(-1) = -1 + k + 3 + k + 2$$
Step 4: Combine like terms.
Collecting all terms:
$$p(-1) = -1 + 3 + 2 + k + k = 4 + 2k$$
Step 5: Set the polynomial equal to zero and solve for $k$.
Since $(x+1)$ is a factor, we must have $p(-1) = 0$:
$$4 + 2k = 0$$
$$2k = -4$$
$$k = -2$$
Step 6: State the final answer.
The value of $k$ is $\boxed{-2}$, which corresponds to **Option 3**.
Correct Answer: 3