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Ch. 5 - Systems and Matrices
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 6, Problem 42

Determine the system of equations illustrated in each graph. Write equations in standard form.
Graph showing two intersecting lines with points labeled (5/2, 1/2) and (2, 3) on the coordinate plane.

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1
Identify two points on the first line. From the graph, these points are (-8, 0) and (-4, 0).
Calculate the slope of the first line using the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\). Since both points have \(y=0\), the slope is \(m = 0\).
Write the equation of the first line in slope-intercept form: \(y = 0\). Convert this to standard form: \(y = 0\) or \(0x + y = 0\).
Identify two points on the second line. From the graph, these points are (0, 10) and (0, -3).
Calculate the slope of the second line using the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\). Since both points have \(x=0\), the slope is undefined, indicating a vertical line. The equation is \(x = 0\) in standard form.

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Key Concepts

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

Finding the Equation of a Line from Intercepts

A line can be determined using its x- and y-intercepts by applying the intercept form of a linear equation. The formula is \( \frac{x}{a} + \frac{y}{b} = 1 \), where \(a\) and \(b\) are the x- and y-intercepts respectively. This form helps quickly write the equation when intercepts are known from the graph.
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Graphing Lines in Slope-Intercept Form

Converting to Standard Form of a Linear Equation

The standard form of a linear equation is \(Ax + By = C\), where A, B, and C are integers, and A ≥ 0. After finding the equation from intercepts or slope-intercept form, rearranging terms to this form is essential for consistency and comparison of linear equations.
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Converting Standard Form to Vertex Form

Interpreting Graphs to Identify Systems of Equations

A system of equations consists of two or more linear equations graphed on the same coordinate plane. Understanding how to read points, intercepts, and slopes from the graph allows one to write each equation accurately and analyze their intersection points, which represent solutions to the system.
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Introduction to Systems of Linear Equations