Chapter 2: Problem 43
Find the slope and \(y\)-intercept of the line and draw its graph. \(x+3 y=0\)
Short Answer
Expert verified
Slope is \(-\frac{1}{3}\) and \(y\)-intercept is 0.
Step by step solution
01
Convert to Slope-Intercept Form
First, rearrange the equation into the slope-intercept form, which is \(y = mx + b\), where \(m\) is the slope and \(b\) is the \(y\)-intercept. Start with the original equation:\[ x + 3y = 0 \]Subtract \(x\) from both sides:\[ 3y = -x \]Next, divide every term by 3 to solve for \(y\):\[ y = -\frac{1}{3}x \]
02
Identify the Slope and Y-intercept
In the equation \(y = -\frac{1}{3}x\), compare with \(y = mx + b\) to find the slope \(m\) and \(y\)-intercept \(b\).- Slope \(m = -\frac{1}{3}\)- \(y\)-intercept \(b = 0\) (since there is no constant term).
03
Draw the Graph
To graph the equation, start by plotting the y-intercept (0,0) on the graph since \(b = 0\).Next, use the slope to determine the rise over run. The slope \(-\frac{1}{3}\) means for every 3 units you move horizontally to the right, you move 1 unit downwards.Start from (0,0):1. Move 3 units to the right to (3, 0).2. Then move 1 unit down to (3, -1).Draw the line through these points.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
The slope-intercept form of a linear equation is one of the most straightforward ways to express a line. It is written as \( y = mx + b \). In this equation:
- \( m \) represents the slope of the line.
- \( b \) is the y-intercept, which is where the line crosses the y-axis.
Slope
In the context of a line, the slope is a measure of its steepness and direction. The slope \( m \) is calculated as the ratio of the vertical change (rise) to the horizontal change (run) between two points on the line. A positive slope indicates an upward trend as you move from left to right, whereas a negative slope shows a downward trend. When we have the equation \( y = -\frac{1}{3}x \), the slope is \( -\frac{1}{3} \). This tells us:
- The line travels downward as it moves from left to right.
- For every 3 units of horizontal movement to the right, there's a 1 unit decline vertically.
Y-intercept
The y-intercept of a line is the point on the graph where the line crosses the y-axis. It is represented by \( b \) in the slope-intercept form equation \( y = mx + b \). In practical terms, it's the value of \( y \) when \( x \) is zero.In our specific example with the equation \( y = -\frac{1}{3}x \), there is no constant term, which indicates that the y-intercept \( b \) is 0. This tells us that the line passes through the origin of the graph (0,0), which is an essential anchor point for plotting the line initially. Knowing the y-intercept helps in positioning the line accurately from the start when graphing.
Graphing Linear Equations
Graphing a linear equation involves representing it visually on a coordinate plane. The first step involves identifying the y-intercept and plotting this point. For the equation \( y = -\frac{1}{3}x \), the y-intercept is (0,0). Next, utilize the slope to find another point on the line. Since the slope is \( -\frac{1}{3} \), start at the y-intercept:
- Move 3 units right horizontally (the 'run').
- Then, move 1 unit down vertically (the 'rise').