Math Problem Statement

Determine the inverse of the matrix C = [ [-2, 3], [-2, 8] ]

Solution

To find the inverse of a 2x2 matrix CC, we can use the following formula for the inverse of a matrix A=(abcd)A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}:

A1=1adbc(dbca)A^{-1} = \frac{1}{ad - bc} \begin{pmatrix} d & -b \\ -c & a \end{pmatrix}

In this case, the matrix CC is given as:

C=(2328)C = \begin{pmatrix} -2 & 3 \\ -2 & 8 \end{pmatrix}

Let's apply the formula step by step:

  1. Compute the determinant:
    The determinant of a 2x2 matrix is calculated as:

    det(C)=(2)(8)(3)(2)=16+6=10\text{det}(C) = (-2)(8) - (3)(-2) = -16 + 6 = -10

  2. Use the inverse formula:
    Now, use the formula for the inverse:

    C1=110(8322)C^{-1} = \frac{1}{-10} \begin{pmatrix} 8 & -3 \\ 2 & -2 \end{pmatrix}

    Multiplying by 110\frac{1}{-10}:

    C1=(810310210210)C^{-1} = \begin{pmatrix} \frac{8}{-10} & \frac{-3}{-10} \\ \frac{2}{-10} & \frac{-2}{-10} \end{pmatrix}

  3. Simplify the fractions:
    Simplifying the fractions:

    C1=(453101515)C^{-1} = \begin{pmatrix} \frac{-4}{5} & \frac{3}{10} \\ \frac{1}{5} & \frac{-1}{5} \end{pmatrix}

So, the inverse matrix is:

C1=(453101515)C^{-1} = \begin{pmatrix} \frac{-4}{5} & \frac{3}{10} \\ \frac{1}{5} & \frac{-1}{5} \end{pmatrix}

Would you like more details or have any questions about the solution?

Here are some related questions for practice:

  1. How do you compute the inverse of a 3x3 matrix?
  2. What happens if the determinant of a matrix is zero?
  3. How can matrix inverses be used to solve systems of equations?
  4. What is the relationship between the determinant and the invertibility of a matrix?
  5. How do you interpret the inverse of a transformation matrix in geometry?

Tip: The inverse of a matrix exists only if the determinant is non-zero!

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Inversion

Formulas

Inverse of a 2x2 matrix: A^{-1} = (1 / (ad - bc)) * [ [d, -b], [-c, a] ]
Determinant of a 2x2 matrix: det(A) = ad - bc

Theorems

Matrix Inversion Theorem
Properties of Determinants

Suitable Grade Level

Grades 10-12