Question: Question 16
The polynomial $f(x) = 5x^4 + 9x^3 - 7x^2 + wx - 3$ is divided by $(x + 2)$. For what value of $w$ will the remainder be 3?
$w =$
1. **State the problem:** We want to find the value of $w$ such that when the polynomial $$f(x) = 5x^4 + 9x^3 - 7x^2 + wx - 3$$ is divided by $x + 2$, the remainder is 3.
2. **Recall the Remainder Theorem:** When a polynomial $f(x)$ is divided by $x - a$, the remainder is $f(a)$. Here, the divisor is $x + 2$, which can be rewritten as $x - (-2)$, so $a = -2$.
3. **Apply the Remainder Theorem:** The remainder when dividing by $x + 2$ is $f(-2)$. We want:
$$f(-2) = 3$$
4. **Calculate $f(-2)$:**
$$f(-2) = 5(-2)^4 + 9(-2)^3 - 7(-2)^2 + w(-2) - 3$$
Calculate powers:
$$(-2)^4 = 16$$
$$(-2)^3 = -8$$
$$(-2)^2 = 4$$
Substitute:
$$f(-2) = 5 \times 16 + 9 \times (-8) - 7 \times 4 + w \times (-2) - 3$$
Simplify:
$$= 80 - 72 - 28 - 2w - 3$$
Combine constants:
$$80 - 72 = 8$$
$$8 - 28 = -20$$
$$-20 - 3 = -23$$
So:
$$f(-2) = -23 - 2w$$
5. **Set remainder equal to 3:**
$$-23 - 2w = 3$$
6. **Solve for $w$:**
Add 23 to both sides:
$$-2w = 3 + 23$$
$$-2w = 26$$
Divide both sides by $\cancel{-2}$:
$$w = \frac{26}{\cancel{-2}} \times \cancel{-1} = -13$$
7. **Final answer:**
$$\boxed{w = -13}$$