Math Problem Statement

Given matrix B = [[3x, x], [2x, x/2]], determine possible values of x if |B| = -8 under the condition that B is singular.

Solution

To solve this problem, we need to address two main points:

  1. The matrix BB is given as: B=[3xx2xx2]B = \begin{bmatrix} 3x & x \\ 2x & \frac{x}{2} \end{bmatrix}

  2. We need to determine the possible values of xx such that the determinant B=8|B| = -8 and BB is singular.

Steps to Solution

Step 1: Calculate the Determinant of BB

For a 2×22 \times 2 matrix of the form: [abcd]\begin{bmatrix} a & b \\ c & d \end{bmatrix} the determinant is calculated as: B=adbc|B| = ad - bc

In this case:

  • a=3xa = 3x
  • b=xb = x
  • c=2xc = 2x
  • d=x2d = \frac{x}{2}

So the determinant of BB is: B=(3x)(x2)(x)(2x)|B| = (3x) \left(\frac{x}{2}\right) - (x)(2x) Expanding this: B=3x222x2|B| = \frac{3x^2}{2} - 2x^2

To simplify further, convert 2x22x^2 to have a common denominator: B=3x224x22=x22|B| = \frac{3x^2}{2} - \frac{4x^2}{2} = \frac{-x^2}{2} Thus: B=x22|B| = -\frac{x^2}{2}

Step 2: Set the Determinant to 8-8

Since we are given B=8|B| = -8, substitute this into our equation: x22=8-\frac{x^2}{2} = -8

Multiply both sides by 2-2: x2=16x^2 = 16

Taking the square root of both sides, we get: x=±4x = \pm 4

Step 3: Check the Condition for BB to be Singular

A matrix is singular if its determinant is zero. However, since we are given a specific non-zero value for the determinant (8-8), this means the condition of singularity here might be a misunderstanding, or they intended to highlight the calculation with B=8|B| = -8 explicitly rather than enforcing singularity directly.

Final Answer

The possible values of xx are: x=±4x = \pm 4

Would you like a deeper explanation on any specific part of this solution?


Here are some additional questions to consider:

  1. How would the solution change if the matrix BB were required to be singular?
  2. What is the determinant when x=0x = 0, and does it satisfy any conditions?
  3. What is the significance of the matrix being singular in this problem?
  4. How do we interpret complex solutions if any arise in a similar problem?
  5. What other methods can be used to verify the determinant calculations?

Tip: When working with determinants, always check if a matrix can be simplified before computation for faster results.

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Math Problem Analysis

Mathematical Concepts

Determinants
Matrices
Algebra

Formulas

Determinant of a 2x2 matrix formula: |B| = ad - bc

Theorems

-

Suitable Grade Level

Undergraduate