Use the inverse matrix method to solve the following: 2p - 4q = -14 2q - 3p = 13 Describe each of the following types of sets: disjoint

Question image

Understand the Problem

The question asks to solve a system of two linear equations with two variables (p and q) using the inverse matrix method. The second question requires the definition of disjoint sets.

Answer

$p = -3$ $q = 2$ Disjoint sets have no elements in common.
Answer for screen readers

$p = -3$ $q = 2$ Disjoint sets are sets having no element in common.

Steps to Solve

  1. Rewrite the equations in standard form

Rearrange the second equation to match the order of variables in the first equation. The original equations are: $2p - 4q = -14$ $2q - 3p = 13$ Rewriting the second equation: $-3p + 2q = 13$

  1. Express the system of equations in matrix form

The system can be written as $AX = B$, where $A = \begin{bmatrix} 2 & -4 \ -3 & 2 \end{bmatrix}$, $X = \begin{bmatrix} p \ q \end{bmatrix}$, and $B = \begin{bmatrix} -14 \ 13 \end{bmatrix}$.

  1. Calculate the determinant of matrix $A$

The determinant of a 2x2 matrix $\begin{bmatrix} a & b \ c & d \end{bmatrix}$ is $ad - bc$. So, $\det(A) = (2)(2) - (-4)(-3) = 4 - 12 = -8$.

  1. Calculate the inverse of matrix A

The inverse of a 2x2 matrix $\begin{bmatrix} a & b \ c & d \end{bmatrix}$ is $\frac{1}{ad-bc} \begin{bmatrix} d & -b \ -c & a \end{bmatrix}$. Therefore, $A^{-1} = \frac{1}{-8} \begin{bmatrix} 2 & 4 \ 3 & 2 \end{bmatrix} = \begin{bmatrix} -1/4 & -1/2 \ -3/8 & -1/4 \end{bmatrix}$.

  1. Solve for $X$ using $X = A^{-1}B$

Multiply the inverse of A by B to find the values of p and q. $X = \begin{bmatrix} -1/4 & -1/2 \ -3/8 & -1/4 \end{bmatrix} \begin{bmatrix} -14 \ 13 \end{bmatrix}$ $X = \begin{bmatrix} (-1/4)(-14) + (-1/2)(13) \ (-3/8)(-14) + (-1/4)(13) \end{bmatrix} = \begin{bmatrix} 14/4 - 13/2 \ 42/8 - 13/4 \end{bmatrix} = \begin{bmatrix} 7/2 - 13/2 \ 21/4 - 13/4 \end{bmatrix} = \begin{bmatrix} -6/2 \ 8/4 \end{bmatrix} = \begin{bmatrix} -3 \ 2 \end{bmatrix}$ Therefore, $p = -3$ and $q = 2$.

  1. Define disjoint sets

Disjoint sets are sets that have no elements in common. In other words, their intersection is the empty set.

$p = -3$ $q = 2$ Disjoint sets are sets having no element in common.

More Information

The inverse matrix method is a useful technique to solve systems of linear equations, especially when dealing with larger systems that can be efficiently represented in matrix form. Disjoint sets are fundamental in set theory and probability.

Tips

A common mistake is incorrectly calculating the determinant or inverse of the matrix. Carefully follow the formulas, and double-check your arithmetic. Also, ensure the equations are in standard form before creating the matrices.

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