Find the value of k so that the remainder = 0. 3 2 (x + 18x + kx + 4) = (x + 2)

Algebra and Trigonometry (6th Edition)
6th Edition
ISBN:9780134463216
Author:Robert F. Blitzer
Publisher:Robert F. Blitzer
ChapterP: Prerequisites: Fundamental Concepts Of Algebra
Section: Chapter Questions
Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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**Problem Statement:**

Find the value of \( k \) so that the remainder is zero when dividing the polynomial \( (x^3 + 18x^2 + kx + 4) \) by \( (x + 2) \).

**Explanation:**

To solve this problem, we can use the Remainder Theorem. The theorem states that the remainder of the division of a polynomial \( f(x) \) by a linear divisor \( (x - a) \) is equal to \( f(a) \).

Here, the divisor is \( (x + 2) \), which can be written as \( (x - (-2)) \). Therefore, according to the Remainder Theorem, the remainder will be zero if \( f(-2) = 0 \).

**Steps:**

1. Substitute \( x = -2 \) into the polynomial \( f(x) = x^3 + 18x^2 + kx + 4 \).

2. Calculate the result: 
   \[
   (-2)^3 + 18(-2)^2 + k(-2) + 4 = 0
   \]

3. Simplify and solve the equation for \( k \):
   \[
   -8 + 18(4) - 2k + 4 = 0
   \]

4. Combine like terms:
   \[
   -8 + 72 - 2k + 4 = 0
   \]

5. \(-8 + 72 + 4 = 68\), so:
   \[
   68 - 2k = 0
   \]

6. Solve for \( k \):
   \[
   2k = 68 
   \]
   \[
   k = 34
   \]

Thus, the value of \( k \) is 34 for the remainder to be zero.
Transcribed Image Text:**Problem Statement:** Find the value of \( k \) so that the remainder is zero when dividing the polynomial \( (x^3 + 18x^2 + kx + 4) \) by \( (x + 2) \). **Explanation:** To solve this problem, we can use the Remainder Theorem. The theorem states that the remainder of the division of a polynomial \( f(x) \) by a linear divisor \( (x - a) \) is equal to \( f(a) \). Here, the divisor is \( (x + 2) \), which can be written as \( (x - (-2)) \). Therefore, according to the Remainder Theorem, the remainder will be zero if \( f(-2) = 0 \). **Steps:** 1. Substitute \( x = -2 \) into the polynomial \( f(x) = x^3 + 18x^2 + kx + 4 \). 2. Calculate the result: \[ (-2)^3 + 18(-2)^2 + k(-2) + 4 = 0 \] 3. Simplify and solve the equation for \( k \): \[ -8 + 18(4) - 2k + 4 = 0 \] 4. Combine like terms: \[ -8 + 72 - 2k + 4 = 0 \] 5. \(-8 + 72 + 4 = 68\), so: \[ 68 - 2k = 0 \] 6. Solve for \( k \): \[ 2k = 68 \] \[ k = 34 \] Thus, the value of \( k \) is 34 for the remainder to be zero.
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