/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 2 Find each determinant. Do not us... [FREE SOLUTION] | 91Ó°ÊÓ

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Find each determinant. Do not use a calculator. $$\operatorname{det}\left[\begin{array}{ll}-1 & 3 \\\\-2 & 9\end{array}\right]$$

Short Answer

Expert verified
The determinant is -3.

Step by step solution

01

Understand the formula for a 2x2 determinant

For a 2x2 matrix \( \begin{bmatrix} a & b \ c & d \end{bmatrix} \), the determinant \( \text{det}(A) \) is calculated as \( ad - bc \).
02

Identify the values in the matrix

Identify \( a = -1 \), \( b = 3 \), \( c = -2 \), and \( d = 9 \) from the matrix \( \begin{bmatrix} -1 & 3 \ -2 & 9 \end{bmatrix} \).
03

Substitute values into the determinant formula

Using the determinant formula \( ad - bc \), substitute: \((-1)(9) - (3)(-2)\).
04

Calculate each part separately

First calculate \((-1)(9) = -9\), and then calculate \((3)(-2) = -6\).
05

Solve the expression for the determinant

Combine the results: \(-9 - (-6) = -9 + 6 = -3\).

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Key Concepts

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

2x2 Matrix
A 2x2 matrix, in its simplest form, is a compact and organized array with two rows and two columns. It looks something like this:\[\begin{bmatrix}a & b \c & d\end{bmatrix}\]In this matrix:
  • The first row consists of elements \(a\) and \(b\).
  • The second row consists of elements \(c\) and \(d\).
These elements can be numbers, expressions, or even symbols that represent specific quantities.
The beauty of the 2x2 matrix lies in its simplicity and its wide range of applications, from solving systems of linear equations to representing transformations in graphics.
Understanding the arrangement and significance of each element in the matrix is essential as it forms the basis for further mathematical operations and analyses.
Determinant Formula
The determinant of a 2x2 matrix provides significant insight into the properties of the matrix. It's calculated using a simple yet effective formula:\[\text{det}(A) = ad - bc\]Here, \(a\), \(b\), \(c\), and \(d\) are the elements of the matrix \(\begin{bmatrix}a & b \c & d\end{bmatrix}\).
  • \(ad\) is the product of the diagonal elements \(a\) and \(d\).
  • \(bc\) is the product of the non-diagonal elements \(b\) and \(c\).
  • The determinant is found by subtracting \(bc\) from \(ad\).
This calculation might seem straightforward, but it carries a deeper meaning.
If the determinant is zero, it indicates the matrix does not have an inverse, and the transformation it represents is not reversible. On the other hand, a nonzero determinant suggests that the matrix is invertible, and the corresponding transformation preserves distinct positions.
Mastering the determinant formula is crucial for analyzing and understanding the characteristics of matrices.
Matrix Mathematics
Matrix mathematics serves as a cornerstone in several branches of mathematics and applied sciences. At its core, it deals with arrays like our 2x2 matrix and employs operations such as addition, subtraction, multiplication, and finding determinants.
Matrices can represent and solve problems involving multiple variables with ease.
  • They are utilized in systems of equations, which may appear daunting without the organized structure that matrices provide.
  • In computer graphics, matrices transform and manipulate images and shapes.
  • In physics, matrices describe movements and changes in mechanics and quantum state behaviors.
The calculation of determinants, as seen in the determinant formula, is an essential part of matrix mathematics. It allows us to find solutions to matrix equations and determine properties like invertibility.
By understanding matrix mathematics, we develop the skills to tackle complex mathematical problems efficiently and elegantly.

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Most popular questions from this chapter

From January to June \(2012,\) Samsung and Apple spent a combined 293 million dollars on media. Apple spent 93 million dollars more than Samsung. (a) Write a system of equations whose solution gives the spending of each media company, in millions of dollars. Let \(x\) be the amount spent by Apple and \(y\) be the amount spent by Samsung. (b) Solve the system of equations. (c) Interpret the solution.

Solve each system graphically. Give \(x\) - and y-coordinates correct to the nearest hundredth. $$\begin{aligned}&y=\log (x+5)\\\&y=x^{2}\end{aligned}$$

The current and estimated resident populations, \(y,\) (in percent) of Black and Spanish/Hispanic/Latino people in the United States for the years \(1990-2050\) are modeled by the following linear equations. $$\begin{aligned}&y=0.0515 x+12.3\\\&y=0.255 x+9.01\end{aligned}$$ In each case, \(x\) represents the number of years since 1990 . (Source: U.S. Census Bureau.) (a) Solve the system to find the year when these population percents were equal. (b) What percent of the U.S. resident population will be Spanish/Hispanic/Latino in the year found in part (a) (c) Graphically support the analytic solution in part (a). (d) Which population is increasing more rapidly?

Given a square matrix \(A^{-1}\), find matrix \(A\). $$A^{-1}=\left[\begin{array}{rr} \frac{3}{20} & \frac{1}{4} \\ -\frac{1}{20} & \frac{1}{4} \end{array}\right]$$

Concept Check Fill in each blank with the appropriate response. The graph of the system $$ y > x^{2}+2 $$ $$ \begin{array}{r} x^{2}+y^{2}<16 \\ y<7 \end{array} $$ consists of all points \(\frac{\text { the parabola given by }}{\text { (above/below) }}\) \(y=x^{2}+2, \frac{ }{\text { (inside/outside) }}\) the circle \(x^{2}+y^{2}=16,\) and (above/below) the line \(y =7\)

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