Math Problem Statement

(x - 2) is a factor of 2x^3 + ax^2 + bx - 2. When the expression is divided by (x + 3), the remainder is -50. Find the values of a and b.

Solution

The problem states:

  • (x2)(x - 2) is a factor of 2x3+ax2+bx22x^3 + ax^2 + bx - 2.
  • When the expression is divided by (x+3)(x + 3), the remainder is 50-50.
  • You are required to find the values of aa and bb.

Let me solve this step by step.


Step 1: Using the fact that x2x - 2 is a factor

Since x2x - 2 is a factor, substituting x=2x = 2 into the polynomial P(x)P(x) gives: P(2)=0.P(2) = 0.

The polynomial is P(x)=2x3+ax2+bx2P(x) = 2x^3 + ax^2 + bx - 2. Substituting x=2x = 2: 2(2)3+a(2)2+b(2)2=0.2(2)^3 + a(2)^2 + b(2) - 2 = 0. 16+4a+2b2=0.16 + 4a + 2b - 2 = 0. 4a + 2b + 14 = 0. \tag{1}


Step 2: Using the remainder when divided by (x+3)(x + 3)

The remainder when the polynomial is divided by (x+3)(x + 3) is 50-50. Substituting x=3x = -3 into P(x)P(x), we get: P(3)=50.P(-3) = -50.

Substituting x=3x = -3 into P(x)=2x3+ax2+bx2P(x) = 2x^3 + ax^2 + bx - 2: 2(3)3+a(3)2+b(3)2=50.2(-3)^3 + a(-3)^2 + b(-3) - 2 = -50. 2(27)+a(9)+b(3)2=50.2(-27) + a(9) + b(-3) - 2 = -50. 54+9a3b2=50.-54 + 9a - 3b - 2 = -50. 9a3b56=50.9a - 3b - 56 = -50. 9a - 3b - 6 = 0. \tag{2}


Step 3: Solving the system of equations

From Equation (1): 4a + 2b + 14 = 0 \quad \Rightarrow \quad 2a + b = -7. \tag{3}

From Equation (2): 9a - 3b - 6 = 0 \quad \Rightarrow \quad 3a - b = 2. \tag{4}

Adding Equations (3) and (4): 2a+b+3ab=7+2.2a + b + 3a - b = -7 + 2. 5a=5a=1.5a = -5 \quad \Rightarrow \quad a = -1.

Substitute a=1a = -1 into Equation (3): 2(1)+b=7.2(-1) + b = -7. 2+b=7b=5.-2 + b = -7 \quad \Rightarrow \quad b = -5.


Final Answer

The values of aa and bb are: a=1 and b=5.\boxed{a = -1 \text{ and } b = -5.}


Would you like a more detailed breakdown of the steps, or do you have further questions?

Related Questions

  1. How do you confirm if a polynomial is divisible by a factor like (xc)(x - c)?
  2. What is the Remainder Theorem, and how is it applied in this problem?
  3. Can you graphically represent this polynomial with a=1a = -1 and b=5b = -5?
  4. How do changes in coefficients aa and bb affect the behavior of the polynomial?
  5. What other methods can be used to solve polynomial factorization problems?

Tip

Always substitute given values into polynomials carefully to avoid sign errors, especially when working with cube terms!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Polynomials
Factor Theorem
Remainder Theorem
Systems of Equations

Formulas

P(c) = 0 when (x - c) is a factor
Remainder Theorem: R = P(c) when dividing by (x - c)
Solving linear equations: ax + by = c

Theorems

Factor Theorem
Remainder Theorem

Suitable Grade Level

Grades 10-12