Chapter 3: Problem 7
Graph the given functions. $$y=2 x-4$$
Short Answer
Expert verified
Plot the y-intercept at (0, -4) and use the slope 2 to plot another point, like (1, -2), then connect these points with a straight line.
Step by step solution
01
Identify the Type of Function
The given function is in the form of a linear equation: \( y = mx + c \), where \( m \) is the slope and \( c \) is the y-intercept. In this case, \( m = 2 \) and \( c = -4 \).
02
Determine the Y-Intercept
The y-intercept is the point where the graph crosses the y-axis. Since \( c = -4 \), the y-intercept is at the point (0, -4).
03
Determine the Slope
The slope \( m \) of the line is 2, which means for every 1 unit increase in \( x \), the value of \( y \) increases by 2 units. This tells us the steepness and direction of the line.
04
Plot the Y-Intercept
Draw a point at the y-intercept on the graph at (0, -4). This is the starting point for our line.
05
Use the Slope to Find Another Point
From the point (0, -4), use the slope to find another point on the line. Since the slope is 2, move 1 unit to the right (along the x-axis) and 2 units up to find the next point at (1, -2).
06
Draw the Line
Connect the y-intercept (0, -4) and the point (1, -2) with a straight line, extending in both directions. This line represents the graph of the equation \( y = 2x - 4 \).
07
Verify Correctness
Choose another value for \( x \) to ensure the line is correct. If \( x = 2 \), then \( y = 2(2) - 4 = 0 \). Plot (2, 0) and see if it lies on the line. It should match the line drawn.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Linear Equations
Graphing linear equations involves drawing a visual representation of the relationship defined by a linear equation. Linear equations have the general form \( y = mx + c \), where \( m \) is the slope and \( c \) is the y-intercept.To graph a linear equation like \( y = 2x - 4 \):
- Identify the y-intercept. This is where the graph crosses the y-axis. For this equation, it's at point (0, -4).
- Determine the slope. A slope of 2 means the line rises 2 units for every 1 unit it moves to the right.
- Use the slope to find another point. From (0, -4), move 1 unit right and 2 units up to find (1, -2).
- Draw a straight line through the points to extend the graph in both directions.
Slope-Intercept Form
The slope-intercept form \( y = mx + c \) is a powerful way to express linear equations. It clearly shows both the slope and the y-intercept, making it easy to graph:
- The slope \( m \) indicates the line's steepness and direction. A positive slope means the line rises as you move right, while a negative slope means it falls.
- The y-intercept \( c \) represents where the line crosses the y-axis. For example, in \( y = 2x - 4 \), the y-intercept is -4, at point (0, -4).
Plotting Points
Plotting points involves marking specific coordinates on a graph to visually represent data or functions. It starts with understanding the Cartesian plane, where:
- Each point is represented by an \( (x, y) \) coordinate.
- The x-coordinate shows the horizontal position, while the y-coordinate shows the vertical position.
Linear Equation Graphing
Linear equation graphing transforms theoretical equations into concrete visual forms. This technique allows us to observe patterns and predict trends between variables:
- Start by plotting known points, usually the y-intercept, and then any additional points found using the slope.
- Connect these points with a straight line that stretches infinitely in both directions, symbolizing the equation's continuous nature.