Chapter 4: Problem 12
Determine if each pair of lines is parallel, perpendicular, or neither. $$\begin{array}{l}y-2 x=3 \\\x+2 y=3\end{array}$$
Short Answer
Expert verified
The given lines are perpendicular since their slopes are negative reciprocals of each other, with \(m_{1} = 2\) and \(m_{2} = -\frac{1}{2}\), satisfying the condition \(m_1 * m_2 = -1\).
Step by step solution
01
Put the given equations in the slope-intercept form \(y = mx + b\)
To put the given equations in the slope-intercept form, we need to solve for y. We have the following equations:
$$\begin{array}{l}y-2 x=3 \\\x+2 y=3\end{array}$$
For the first equation:
$$y = 2x + 3$$
For the second equation:
$$2y = -x + 3 \Rightarrow y = -\frac{1}{2}x + \frac{3}{2}$$
Now, we have the following slope-intercept forms of the given equations:
$$\begin{array}{l}y=2 x+3 \\\y=-\frac{1}{2}x+\frac{3}{2}\end{array}$$
02
Identify the slopes (m) of both lines
To identify the slopes, we can simply look at the coefficients of the x terms in the slope-intercept form. For the first line, we have:
$$y = 2x+3$$
The slope of this line is equal to 2. For the second line, we have:
$$y = -\frac{1}{2}x + \frac{3}{2}$$
The slope of the second line is equal to -1/2.
03
Compare the slopes
Now that we have the slopes of both lines, we can compare them to see their relationship. The slopes are:
First line: m1 = 2
Second line: m2 = -1/2
04
Determine if the lines are parallel, perpendicular, or neither
Using the relationship between the slopes, we can determine if the lines are parallel, perpendicular, or neither.
Parallel: The lines are parallel if their slopes are equal.
m1 = m2
Perpendicular: The lines are perpendicular if their slopes are negative reciprocals of each other.
m1 * m2 = -1
Neither: The lines are neither parallel nor perpendicular if their slopes do not meet either of these conditions.
Comparing the slopes of our given lines, we can see that:
- m1 ≠m2 (The lines are not parallel)
- m1 * m2 = 2 * (-1/2) = -1 (The lines are perpendicular)
Since the product of the slopes is -1, we can conclude that the given lines are perpendicular to each other.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
Understanding the slope-intercept form is essential in analyzing and graphing linear equations. The standard expression for this form is \(y = mx + b\), where:
- \(m\) represents the slope of the line, which shows the rate of change or the steepness of the line.
- \(b\) is the y-intercept, which is the point where the line crosses the y-axis.
- Solving for \(y\) will show the slope and y-intercept directly.
- It simplifies the process of graphing the line on a coordinate plane.
Linear Equations
Linear equations are equations of the first degree, meaning they have no exponents higher than 1 and graph as straight lines on a coordinate plane. They can be expressed in various forms, with the slope-intercept being one of the most common. The general approach to solving linear equations involves:
- Rearranging the equation to isolate one of the variables, typically \(y\).
- Balancing both sides of the equation to maintain equality.
Algebraic Expressions
Algebraic expressions are combinations of numbers, variables, and operators (such as addition and multiplication) that represent a specific value. In the realm of linear equations, they form the basis of expressing relationships between variables. Tasks involving algebraic expressions often include:
- Collecting like terms to simplify expressions.
- Isolating variables by applying operations to both sides of an equation.
Slope Comparison
Comparing slopes is crucial when determining the relationship between two lines. The slope of a line describes its steepness and direction:
- Parallel lines have identical slopes, indicating they will never intersect.
- Perpendicular lines have slopes that are negative reciprocals of each other, meaning their product is -1.
- If slopes don’t fit either criterion, lines are neither parallel nor perpendicular.