Chapter 3: Problem 80
Graph equation. Solve for \(y\) first, when necessary. \(y=-3.5 x+4\)
Short Answer
Expert verified
The graph is a straight line with a slope of -3.5, crossing the y-axis at 4.
Step by step solution
01
Identify the Equation Type
The equation given is in the form of a linear equation, commonly written as \( y = mx + b \), where \( m \) represents the slope and \( b \) represents the y-intercept.
02
Identify the Slope and Y-intercept
For the equation \( y = -3.5x + 4 \), the slope \( m \) is -3.5, and the y-intercept \( b \) is 4. This means the line crosses the y-axis at \( y = 4 \).
03
Plot the Y-intercept
On the coordinate plane, plot the point (0,4). This is where the line will intersect the y-axis.
04
Use the Slope to Plot a Second Point
Starting from the y-intercept (0,4), use the slope \( -3.5 \). A slope of \(-3.5\) means you go down 3.5 units and 1 unit to the right from the y-intercept. Plot this second point.
05
Draw the Line
Draw a straight line through the points (0,4) and the point you plotted in Step 4. Extend the line in both directions, ensuring it is straight.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Slope
In the world of linear equations, the slope plays a crucial role. The slope describes how steep a line is. It's often represented by the letter \( m \). When interpreting the slope from the equation \( y = mx + b \), it indicates the rate of change of \( y \) with respect to \( x \).
For the equation \( y = -3.5x + 4 \), the slope is \(-3.5\). But what does this number mean?
For the equation \( y = -3.5x + 4 \), the slope is \(-3.5\). But what does this number mean?
- A negative slope, like \(-3.5\), indicates that the line is decreasing. This means as you move from left to right along the graph, the line goes downwards.
- The value \(3.5\) tells us the exact steepness; for every step right along the x-axis, the line drops 3.5 units.
Demystifying the Y-intercept
The y-intercept is where the magic begins when you start plotting your linear equation on a coordinate plane. It is represented by the symbol \( b \) in the linear equation format \( y = mx + b \).
For the given equation \( y = -3.5x + 4 \), the y-intercept is \(4\). But what exactly does the y-intercept mean and why is it so important?
For the given equation \( y = -3.5x + 4 \), the y-intercept is \(4\). But what exactly does the y-intercept mean and why is it so important?
- The y-intercept gives you the point \((0, b)\) where the line crosses the y-axis. For this equation, the line crosses the y-axis at \((0, 4)\).
- This point is crucial because it serves as a starting point for drawing the line on a graph.
Navigating the Coordinate Plane
The coordinate plane is your canvas for graphing linear equations. It's a two-dimensional plane defined by two perpendicular axes: the x-axis (horizontal) and the y-axis (vertical).
When plotting a linear equation like \( y = -3.5x + 4 \), the coordinate plane helps visualize the relationship between \( x \) and \( y \).
When plotting a linear equation like \( y = -3.5x + 4 \), the coordinate plane helps visualize the relationship between \( x \) and \( y \).
- Start by identifying the y-intercept and marking it on the y-axis. For \( y = -3.5x + 4 \), plot the point \((0, 4)\).
- Use the slope to determine the movement from the y-intercept. With a slope of \(-3.5\), drop 3.5 units for each step right.
- Plot another point using the slope, then draw a line through both points. Extend the line in both directions to cover more of the plane.