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Use matrix inversion to solve the system of equations. $$\left\\{\begin{array}{l}3 x+2 y=-4 \\\4 x+y=3\end{array}\right.$$

Short Answer

Expert verified
The solution to the system of equations is x = 2 and y = 3.

Step by step solution

01

Write the system of equations as a matrix

First, the given system of equations can be written as a matrix multiplication. The matrix \( M \) will contain the coefficients of x and y, and the matrix \( V \) will contain the variables x and y. The right hand side of the equations will be placed in a separate matrix, \( R \). This can be represented as \( M*V = R \). The matrices will be: \(M = \[ \begin{matrix} 3 & 2 \\ 4 & 1 \end{matrix} \] \), \( V = \[ \begin{matrix} x \\ y \end{matrix} \]\), and \( R = \[ \begin{matrix} -4 \\ 3 \end{matrix} \]\).
02

Calculate the inverse of matrix M

The formula to calculate the inverse of a 2 x 2 matrix, given a matrix \( A = \[ \begin{matrix} a & b \\ c & d \end{matrix} \]\) is \( A^{-1} = (1/(ad-bc)) * \[ \begin{matrix} d & -b \\ -c & a \end{matrix} \]\). So, the inverse of matrix M would be \( M^{-1} = (1/(3*1 - 2*4)) * \[ \begin{matrix} 1 & -2 \\ -4 & 3 \end{matrix} \]\), which simplifies to \( M^{-1} = \[ \begin{matrix} -1 & 2 \\ 4 & -3 \end{matrix} \]\).
03

Multiply the inverse M with matrix R

The next step is to post-multiply the reverse of Matrix M with Matrix R. So, \(V = M^{-1}*R = \[ \begin{matrix} -1 & 2 \\ 4 & -3 \end{matrix} \] * \[ \begin{matrix} -4 \\ 3 \end{matrix} \]\), leading to the result \( V = \[ \begin{matrix} x \\ y \end{matrix} \] = \[ \begin{matrix} 2 \\ 3 \end{matrix} \]\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

System of Linear Equations
At the heart of algebra lies the system of linear equations, a collection of two or more linear equations with the same set of variables. To visualize it, consider each linear equation as a straight line on a graph. When dealing with two variables, these lines can either intersect, run parallel, or coincide. The set of points where they intersect represents the solution to the system of equations.

For example, in a system with equations involving variables x and y, we could be looking for a point (x, y) that satisfies both equations simultaneously. The matrix inversion method provides an alternative to graphical and algebraic methods like substitution or elimination. It involves transforming the system into a matrix format to find solutions, which can be computationally more efficient, especially with larger systems.
Matrix Multiplication
Matrix multiplication is a crucial operation that allows us to manipulate systems of equations compactly. Imagine having two matrices, one representing the coefficients of variables in a system (commonly referred to as the coefficient matrix), and another representing the variables themselves. When you multiply these matrices, the resulting matrix equates to the right-hand side values of the system.

To multiply two matrices, the number of columns in the first must match the number of rows in the second. Multiplication is then executed by taking the dot product of rows from the first matrix with columns from the second. The position of each product forms an element of the resulting matrix. This method is not only used in solving equations but also in various applications ranging from computer graphics to economic modeling.
Inverse of a Matrix
Just like division is the inverse operation of multiplication for numbers, the inverse of a matrix serves a similar purpose in the realm of matrices. However, not all matrices have an inverse; only square matrices (same number of rows and columns) that are non-singular (have a non-zero determinant) are invertible.

The inverse of a matrix, when multiplied by the original matrix, yields the identity matrix, which acts like the number 1 in matrix algebra. Finding the inverse involves several steps, such as calculating the determinant, the adjugate, and then applying the formula for the inverse. In the context of solving systems of linear equations, the inverse of the coefficient matrix allows us to isolate the variable matrix by 'dividing' the two sides of the equation. The process demonstrated in the step-by-step solution exemplifies how powerful this method can be, transforming a complex system into a straightforward matrix multiplication problem.

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Most popular questions from this chapter

An electronics firm makes a clock radio in two different models: one (model 380 ) with a battery backup feature and the other (model 360 ) without. It takes 1 hour and 15 minutes to manufacture each unit of the model 380 radio, and only 1 hour to manufacture each unit of the model \(360 .\) At least 500 units of the model 360 radio are to be produced. The manufacturer realizes a profit per radio of \(\$ 15\) for the model 380 and only \(\$ 10\) for the model \(360 .\) If at most 2000 hours are to be allocated to the manufacture of the two models combined, how many of each model should be made to maximize the total profit?

Apply elementary row operations to a matrix to solve the system of equations. If there is no solution, state that the system is inconsistent. $$\left\\{\begin{array}{c}x+2 y+z=-3 \\ 3 x+y-2 z=2 \\ 4 x+3 y-z=0\end{array}\right.$$

A farmer has 90 acres available for planting corn and soybeans. The cost of seed per acre is \(\$ 4\) for corn and \(\$ 6\) for soybeans. To harvest the crops, the farmer will need to hire some temporary help. It will cost the farmer \(\$ 20\) per acre to harvest the corn and \(\$ 10\) per acre to harvest the soybeans. The farmer has \(\$ 480\) available for seed and \(\$ 1400\) available for labor. His profit is \(\$ 120\) per acre of corn and \(\$ 150\) per acre of soybeans. How many acres of each crop should the farmer plant to maximize the profit?

A chemist wishes to make 10 gallons of a \(15 \%\) acid solution by mixing a \(10 \%\) acid solution with a \(25 \%\) acid solution. (a) Let \(x\) and \(y\) denote the total volumes (in gallons) of the \(10 \%\) and \(25 \%\) solutions, respectively. Using the variables \(x\) and \(y,\) write an equation for the total volume of the \(15 \%\) solution (the mixture). (b) Using the variables \(x\) and \(y,\) write an equation for the total volume of acid in the mixture by noting that Volume of acid in \(15 \%\) solution \(=\) volume of acid in \(10 \%\) solution \(+\) volume of acid in \(25 \%\) solution. (c) Solve the system of equations from parts (a) and (b), and interpret your solution. (d) Is it possible to obtain a \(5 \%\) acid solution by mixing a \(10 \%\) solution with a \(25 \%\) solution? Explain without solving any equations.

The sum of the squares of two positive integers is \(85 .\) If the squares of the integers differ by 13 find the integers.

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