Skip to main content
Ch. 5 - Systems and Matrices
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 6, Problem 8

Use the given row transformation to change each matrix as indicated.
[1470],7×row 1 added to row 2\(\left\)[ \(\begin{matrix}\) 1 & -4 \\ 7 & 0 \(\end{matrix}\) \(\right\)], \(\quad\) -7 \(\times\) \(\text{row 1 added to row 2}\)

Verified step by step guidance
1
Identify the given matrix as a 2x2 matrix, which can be represented as \(\begin{bmatrix} a & b \\ c & d \end{bmatrix}\), where \(a\), \(b\), \(c\), and \(d\) are the elements of the matrix.
Understand the row operation: '-7 times row 1 added to row 2' means you multiply each element of row 1 by -7 and then add the result to the corresponding element in row 2.
Write the row operation mathematically as: \(R_2 \rightarrow R_2 + (-7) \times R_1\), where \(R_1\) and \(R_2\) represent row 1 and row 2 respectively.
Apply the operation to each element in row 2: calculate the new element in row 2, column 1 as \(c + (-7) \times a\), and the new element in row 2, column 2 as \(d + (-7) \times b\).
Construct the new matrix after the row operation, keeping row 1 unchanged and replacing row 2 with the new calculated elements.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Elementary Row Operations

Elementary row operations are basic manipulations performed on the rows of a matrix to simplify or solve systems of equations. These include swapping rows, multiplying a row by a nonzero scalar, and adding a multiple of one row to another. Understanding these operations is essential for matrix transformations and solving linear systems.
Recommended video:
Guided course
8:38
Performing Row Operations on Matrices

Matrix Representation and Notation

A matrix is a rectangular array of numbers arranged in rows and columns. Each element is identified by its row and column position. Recognizing how to read and write matrices, especially 2x2 matrices, is crucial for applying row operations correctly and interpreting the results.
Recommended video:
05:18
Interval Notation

Row Transformation: Adding a Multiple of One Row to Another

This specific row operation involves multiplying one row by a scalar and adding it to another row, replacing the latter. For example, '-7 times row 1 added to row 2' means multiply row 1 by -7 and add it to row 2. This operation helps in creating zeros or simplifying matrices during row reduction.
Recommended video:
Guided course
8:38
Performing Row Operations on Matrices