Chapter 1: Problem 75
For each linear equation, a. give the slope \(m\) and \(y\) -intercept \(b\), if any, and b. graph the line. \(y=2 x-3\)
Short Answer
Expert verified
The slope is 2 and the y-intercept is -3.
Step by step solution
01
Identify the Slope-Intercept Form
The given equation is already in the slope-intercept form, which is generally written as \( y = mx + b \). Here, \( m \) represents the slope, and \( b \) is the \( y \)-intercept.
02
Determine the Slope \( m \)
By comparing the given equation \( y = 2x - 3 \) with the slope-intercept form \( y = mx + b \), we identify that the slope \( m \) is \( 2 \).
03
Determine the \( y \)-Intercept \( b \)
In the equation \( y = 2x - 3 \), it is shown that the \( y \)-intercept \( b \) is \( -3 \). This tells us that the line meets the \( y \)-axis at the point (0, -3).
04
Plot the \( y \)-Intercept on the Graph
Start by noting the \( y \)-intercept on the graph. Plot the point (0, -3) on the \( y \)-axis.
05
Use the Slope to Find Another Point
The slope \( m = 2 \) can be rewritten as \( \frac{2}{1} \), indicating a rise of 2 units and a run of 1 unit. From the \( y \)-intercept at (0, -3), move up 2 units and 1 unit to the right to plot another point at (1, -1).
06
Draw the Line
Connect the two points, (0, -3) and (1, -1), with a straight line that extends in both directions. This line represents the graph of the equation \( y = 2x - 3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
Linear equations are often expressed in what is known as the "Slope-Intercept Form." This is a straight-line equation that simplifies graphing and analysis. The general formula is \( y = mx + b \), where:
- \( y \) represents the output or dependent variable.
- \( m \) is the slope, showing the rate of change or steepness of the line.
- \( x \) is the input or independent variable.
- \( b \) is the \( y \)-intercept, which is where the graph crosses the \( y \)-axis.
Slope
The slope of a line indicates its steepness and direction. In the equation \( y = 2x - 3 \), the slope \( m \) is 2. Here's what this means:
- For every increase of 1 in \( x \), \( y \) increases by 2. This is known as "rise over run."
- If the slope is positive, like 2, the line rises from left to right.
- A negative slope would mean the line falls from left to right, indicating a decrease as \( x \) increases.
- A slope of 0 results in a horizontal line, where \( y \) stays constant despite changes in \( x \).
Y-Intercept
The \( y \)-intercept is where the line crosses the \( y \)-axis. In our example equation, \( y = 2x - 3 \), the \( y \)-intercept \( b \) is -3. Here's how to interpret this:
- The line meets the \( y \)-axis at the point \((0, -3)\).
- This point is crucial for graphing as it gives a clear starting point.
- Knowing the \( y \)-intercept allows you to quickly mark the initial point on the graph.
- This helps guide the graphing of the entire line when combined with the slope.
Graphing Linear Equations
Graphing linear equations offers a visual representation of the relationship between variables. To graph \( y = 2x - 3 \):
- Start with the \( y \)-intercept, marked as the point \((0, -3)\).
- Use the slope to find another point. With a slope of 2, move up 2 units and right 1 unit from \((0, -3)\) to reach the point \((1, -1)\).
- Join these two points with a straight line, ensuring it extends in both directions.
- This line represents all the solutions to the equation. Each point on this line is a valid \((x, y)\) pairing that satisfies \( y = 2x - 3 \).