Math Problem Statement

For what value of k makes (x+2) a factor of 2x^3 - 5x^2 + kx + 14?

Solution

To determine the value of kk such that (x+2)(x+2) is a factor of the polynomial 2x35x2+kx+142x^3 - 5x^2 + kx + 14, we use the Factor Theorem. According to this theorem, (x+2)(x+2) is a factor if substituting x=2x = -2 into the polynomial makes the result equal to zero.

Step 1: Substitute x=2x = -2 into the polynomial:

The polynomial is: P(x)=2x35x2+kx+14P(x) = 2x^3 - 5x^2 + kx + 14 Substitute x=2x = -2: P(2)=2(2)35(2)2+k(2)+14P(-2) = 2(-2)^3 - 5(-2)^2 + k(-2) + 14

Step 2: Simplify each term:

2(2)3=2(8)=162(-2)^3 = 2(-8) = -16 5(2)2=5(4)=20-5(-2)^2 = -5(4) = -20 k(2)=2kk(-2) = -2k +14=14+14 = 14

Thus: P(2)=16202k+14P(-2) = -16 - 20 - 2k + 14

Step 3: Combine like terms:

P(2)=(1620+14)2k=222kP(-2) = (-16 - 20 + 14) - 2k = -22 - 2k

Step 4: Set P(2)=0P(-2) = 0 (since x+2x+2 is a factor):

222k=0-22 - 2k = 0

Step 5: Solve for kk:

2k=22k=11-2k = 22 \quad \Rightarrow \quad k = -11

Final Answer:

The value of kk is: 11\boxed{-11}

Would you like further explanation or verification? Let me know!


Related Questions:

  1. What is the Factor Theorem, and how does it work?
  2. How do you determine if a polynomial is divisible by another polynomial?
  3. Can this method be extended to higher-degree factors like (x+a)2(x+a)^2?
  4. What is synthetic division, and how can it be used to verify the factorization?
  5. How does the value of kk affect the overall shape of the polynomial graph?

Tip:

Always double-check factorization problems by substituting the solution back into the polynomial to verify correctness!

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Math Problem Analysis

Mathematical Concepts

Polynomials
Factorization
Substitution

Formulas

P(x) = ax^3 + bx^2 + cx + d
Factor Theorem: P(a) = 0 if (x-a) is a factor

Theorems

Factor Theorem

Suitable Grade Level

Grades 10-12