Chapter 8: Problem 28
For Problems 1-36, graph each linear equation. (Objective 2) $$ 3 x+5 y=-9 $$
Short Answer
Expert verified
Graph the line by plotting points at \((0, -\frac{9}{5})\) and \((5, -\frac{24}{5})\) and drawing a line through them.
Step by step solution
01
Write the Equation in Slope-Intercept Form
To graph the equation, first rewrite it in slope-intercept form, which is \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. Start by isolating \( y \) in the equation \( 3x + 5y = -9 \). Subtract \( 3x \) from both sides to get \( 5y = -3x - 9 \). Then, divide every term by 5 to solve for \( y \): \[ y = -\frac{3}{5}x - \frac{9}{5} \].
02
Identify the Slope and Y-intercept
From the equation \( y = -\frac{3}{5}x - \frac{9}{5} \), identify the slope \( m \) as \(-\frac{3}{5}\) and the y-intercept \( b \) as \(-\frac{9}{5}\). The y-intercept is the point \( (0, -\frac{9}{5}) \) on the graph.
03
Plot the Y-intercept
On the Cartesian plane, plot the y-intercept \( (0, -\frac{9}{5}) \). This is the point where the line crosses the y-axis.
04
Use the Slope to Plot Another Point
Starting from the y-intercept, use the slope \( -\frac{3}{5} \) to find another point. The slope indicates that for every 3 units moved down (because it is negative), move 5 units to the right. From \( (0, -\frac{9}{5}) \), moving 5 units right and 3 units down leads you to the point \( (5, -\frac{24}{5}) \). Plot this point.
05
Draw the Line
With the two points \( (0, -\frac{9}{5}) \) and \( (5, -\frac{24}{5}) \) plotted, draw a straight line through them. Ensure that the line extends in both directions and has arrows to show it continues beyond 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
When dealing with linear equations, the slope-intercept form is a common way to express them. This form makes it easy to graph the equation and understand the line's properties. The general formula for the slope-intercept form is \( y = mx + b \), where:
- \( m \) represents the slope of the line, which indicates how steep the line is.
- \( b \) is the y-intercept, the point where the line crosses the y-axis.
Cartesian Plane
The Cartesian plane is a two-dimensional surface used for graphing equations. It consists of two perpendicular axes:
- The horizontal axis, called the x-axis.
- The vertical axis, called the y-axis.
Plotting Points
Plotting points on the Cartesian plane is a crucial step in graphing equations. Each point is defined by a pair of coordinates \( (x, y) \), indicating its location. To plot a point, simply:
- Find the x-coordinate on the x-axis and mark it.
- From that mark, move vertically to locate the y-coordinate on the y-axis.
- Mark this intersection as a point on the graph.