Chapter 7: Problem 35
Choose a slope and \(y\) -intercept. Write an equation and then graph the line.
Short Answer
Expert verified
The equation is \( y = 2x - 3 \), with a graph starting at \( (0, -3) \) and passing through \( (1, -1) \).
Step by step solution
01
Choose a Slope
Let's choose a slope for the line, which is usually represented by the letter \( m \). For simplicity, let's select \( m = 2 \). This means that for every 1 unit increase in \( x \), \( y \) increases by 2 units.
02
Choose a Y-Intercept
The \( y \)-intercept is where the line crosses the \( y \)-axis. This is represented by \( b \). Let's choose \( b = -3 \). This means that when \( x = 0 \), \( y = -3 \).
03
Write the Equation of the Line
Now that we have a slope \( m = 2 \) and a \( y \)-intercept \( b = -3 \), we can write the equation of the line in the slope-intercept form \( y = mx + b \). Thus, the equation is \( y = 2x - 3 \).
04
Graph the Line
To graph the equation \( y = 2x - 3 \), start by plotting the \( y \)-intercept on the graph at point \( (0, -3) \). Then, use the slope \( m = 2 \) to find another point. From \( (0, -3) \), move up 2 units and to the right 1 unit to reach the next point \( (1, -1) \). Plot this point and draw a line through these two points, extending it in both directions.
05
Verify the Line
Check that the points \( (0, -3) \) and \( (1, -1) \) satisfy the equation \( y = 2x - 3 \). For the point \( (0, -3) \), substitute \( x = 0 \) into the equation: \( y = 2(0) - 3 = -3 \), which is correct. For \( (1, -1) \), substitute \( x = 1 \):\( y = 2(1) - 3 = -1 \), which is also correct. Thus, the line has been correctly graphed.
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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 is one of the most popular ways to express the equation of a straight line. It is written as \( y = mx + b \). Here, \( m \) represents the slope of the line, and \( b \) stands for the \( y \)-intercept. This format is incredibly straightforward, making it easy to understand and use when graphing lines or solving problems involving linear equations.
- **Slope (\( m \)):** This is a measure of the steepness of the line. A larger absolute value indicates a steeper line.
- **Y-Intercept (\( b \)):** This is the point where the line crosses the \( y \)-axis. It provides an easy starting point for graphing the line.
Graphing Lines
Graphing linear equations is a simple process that starts by identifying the \( y \)-intercept and slope from the slope-intercept form equation. Here's a breakdown of how to graph using this form:
- **Start with the \( y \)-intercept:** Locate the \( y \)-intercept on the graph, which is where the graph cuts through the \( y \)-axis. This provides a base point from which to start.
- **Use the Slope:** From the \( y \)-intercept, use the slope to find another point. A slope of \( m = 2 \) indicates that for every 1 unit moved along the \( x \)-axis, the \( y \) value increases by 2 units. This makes it easy to plot additional points quickly.
Y-Intercept
The \( y \)-intercept is a crucial aspect of linear equations and graphing. It gives you the starting point of the line on the graph before considering the slope. When we say a line crosses the \( y \)-axis at \( b \), it means that when \( x = 0 \), the value of \( y \) is \( b \). In practical terms:
- If \( b \) is positive, the line will cross the \( y \)-axis above the origin.
- If \( b \) is zero, the line passes through the origin itself.
- If \( b \) is negative, the line intersects the \( y \)-axis below the origin.