Math Problem Statement

solve using inverse matrix

Solve using inverse matrix: -4x + y = 19 and 3x - 2y = -18

Solution

The system of equations you provided is:

4x+y=19-4x + y = 19 3x2y=183x - 2y = -18

To solve this using the inverse matrix method, we will first write the system of equations in matrix form AX=BA \cdot X = B, where:

A=(4132),X=(xy),B=(1918)A = \begin{pmatrix} -4 & 1 \\ 3 & -2 \end{pmatrix}, \quad X = \begin{pmatrix} x \\ y \end{pmatrix}, \quad B = \begin{pmatrix} 19 \\ -18 \end{pmatrix}

To solve for XX, we use the formula:

X=A1BX = A^{-1} \cdot B

First, we will calculate the inverse of matrix AA, A1A^{-1}. The formula for the inverse of a 2x2 matrix is:

A1=1det(A)(dbca)A^{-1} = \frac{1}{\text{det}(A)} \begin{pmatrix} d & -b \\ -c & a \end{pmatrix} where the matrix AA is given by:

A=(abcd)A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}

For your matrix:

A=(4132)A = \begin{pmatrix} -4 & 1 \\ 3 & -2 \end{pmatrix}

The determinant det(A)\text{det}(A) is calculated as:

det(A)=(ad)(bc)\text{det}(A) = (a \cdot d) - (b \cdot c)

Let's calculate the determinant and then find A1A^{-1}. numpy as np

Define the matrix A

A = np.array([[-4, 1], [3, -2]])

Calculate the determinant of A

det_A = np.linalg.det(A)

Calculate the inverse of A

A_inv = np.linalg.inv(A)

det_A, A_invThe determinant of matrix AA is approximately 5 (det A=5A = 5).

The inverse of matrix AA is:

A1=(0.40.20.60.8)A^{-1} = \begin{pmatrix} -0.4 & -0.2 \\ -0.6 & -0.8 \end{pmatrix}

Next, we will multiply A1A^{-1} by matrix BB to solve for the vector X=(xy)X = \begin{pmatrix} x \\ y \end{pmatrix}:

B=(1918)B = \begin{pmatrix} 19 \\ -18 \end{pmatrix}

Thus, the solution is:

X=A1BX = A^{-1} \cdot B

Let's calculate this multiplication. Define the matrix B B = np.array([19, -18])

Calculate the solution X

X = np.dot(A_inv, B) XThe solution to the system of equations is:

x=4,y=3x = -4, \quad y = 3

Thus, the values of xx and yy are x=4x = -4 and y=3y = 3.

Would you like more details on the solution process, or do you have any other questions? Here are some related questions you might find interesting:

  1. How do you verify the solution to a system of linear equations?
  2. How do you solve a system of linear equations using Gaussian elimination?
  3. What is the geometric interpretation of solving a system of linear equations?
  4. What is the significance of the determinant when using matrix inversion?
  5. How can you solve larger systems of equations using inverse matrices?

Tip: For larger systems, numerical methods like Gaussian elimination or LU decomposition may be more efficient than using the inverse matrix.

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Linear Equations
Matrix Inversion

Formulas

Matrix form of linear equations: A * X = B
Inverse of a 2x2 matrix: A^(-1) = (1/det(A)) * [[d, -b], [-c, a]]
Determinant formula for 2x2 matrix: det(A) = ad - bc

Theorems

Inverse Matrix Theorem

Suitable Grade Level

Grades 11-12