Chapter 7: Problem 7
Solve this system of equations: $$ \left\\{\begin{array}{l} y=|x| \\ y=2.85 \end{array}\right. $$
Short Answer
Expert verified
The solutions are \( x = 2.85 \) and \( x = -2.85 \).
Step by step solution
01
Understand the System of Equations
The system consists of two equations: 1. \( y = |x| \), which describes a V-shaped graph centered at the origin.2. \( y = 2.85 \), a horizontal line crossing the y-axis at \( y = 2.85 \). The solution to the system is where these two equations intersect.
02
Equate the Expressions for y
Since both equations equal \( y \), we can set them equal to each other: \[ |x| = 2.85 \]. This means the positive and negative values of \( x \) that satisfy this equation will be the solutions.
03
Solve for x
The absolute value equation \( |x| = 2.85 \) can be split into two separate equations: 1. \( x = 2.85 \)2. \( x = -2.85 \)We need to consider both cases because of the absolute value.
04
Verify the Solutions
For both solutions, verify by substituting back into each original equation:1. For \( x = 2.85 \), \( y = |2.85| = 2.85 \), and the second equation is \( y = 2.85 \), both match.2. For \( x = -2.85 \), \( y = |-2.85| = 2.85 \), and again \( y = 2.85 \), both match.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Absolute Value
The absolute value of a number represents its distance from zero on a number line, always yielding a non-negative output. The notation for absolute value is given by two vertical bars surrounding the number, such as \(|x|\). To break it down:
- If the value inside the absolute value is positive, the output is the same as the input. For example, \(|5| = 5\).
- If the value inside the absolute value is negative, the output negates the input, making it positive. For instance, \(|-3| = 3\).
Graphical Intersection
Graphical intersection refers to the point or points where two different graphs meet or cross each other on a coordinate plane. In the context of a system of equations, these intersection points represent the solutions to the system.In this exercise, we have:
- The equation \(y = |x|\), which graphs as a V-shaped curve. This is due to the nature of the absolute value—producing a mirror effect along the y-axis.
- The equation \(y = 2.85\), shown as a straight horizontal line that crosses the y-axis at \(2.85\).
Linear Equation
A linear equation is a mathematical statement of equality that forms a straight line when graphed. Typically, it takes the form \(y = mx + b\), where \(m\) represents the slope and \(b\) the y-intercept.In the current problem, the linear equation is \(y = 2.85\). This particular equation forms a horizontal line parallel to the x-axis because it does not incorporate an \(x\) term. Key properties of horizontal lines include:
- The slope is zero, indicating no rise or fall as \(x\) increases.
- It crosses the y-axis at only one point—the y-intercept, here \(y = 2.85\).