Chapter 2: Problem 9
Write an equation for each line in the indicated form. Write the equation in point-slope form for the line that passes through (0,4) and is perpendicular to the line \(x-\) \(2 y=6\).
Short Answer
Expert verified
The equation in point-slope form is \( y - 4 = -2x \).
Step by step solution
01
Convert the Original Equation to Slope-Intercept Form
The given equation is \( x - 2y = 6 \). To find the slope, we first need to rearrange it into slope-intercept form \( y = mx + b \). Begin by solving for \( y \): \(-2y = -x + 6\). Divide every term by \(-2\) to get \( y = \frac{1}{2}x - 3 \). Therefore, the slope of this line is \( \frac{1}{2} \).
02
Find the Slope of the Perpendicular Line
Lines that are perpendicular have slopes that are negative reciprocals of each other. If the slope of the given line is \( \frac{1}{2} \), then the slope of the perpendicular line is the negative reciprocal, which is \(-2\).
03
Use the Point-Slope Formula
The point-slope form of a line is \( y - y_1 = m(x - x_1) \), where \( (x_1, y_1) \) is a point on the line and \( m \) is the slope. We are given the point \((0, 4)\) and the perpendicular slope \(-2\). Substitute these values into the formula: \( y - 4 = -2(x - 0) \).
04
Simplify the Equation
Simplify the equation \( y - 4 = -2(x - 0) \). This simplifies to \( y - 4 = -2x \), which is the point-slope form of the equation.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Perpendicular Lines
Perpendicular lines intersect at a right angle (90 degrees). In the world of coordinate geometry, two lines are perpendicular if the product of their slopes is -1. This means that their slopes are negative reciprocals.
- If you know the slope of one line, you can find the slope of a line perpendicular to it by taking the negative reciprocal.
- For example, if one line has a slope of \( \frac{1}{2} \), then a line perpendicular to it will have a slope of \(-2\).
- This concept is essential when you're trying to determine the relationship between two lines on the coordinate plane.
Slope-Intercept Form
The slope-intercept form of a line gives you a quick way to write the equation of a line. It's expressed as \( y = mx + b \), where:
- \( m \) is the slope of the line, representing the steepness or tilt.
- \( b \) is the y-intercept, which is the point where the line crosses the y-axis.
- The slope \( (m) \) is \( \frac{1}{2} \).
- The y-intercept \( (b) \) is \(-3 \).
Negative Reciprocal
The concept of a negative reciprocal is key when working with perpendicular lines in geometry. To find the negative reciprocal of a number, you follow these steps:
- First, flip the number (take its reciprocal).
- Then, change the sign of the flipped number.
- The reciprocal of \( \frac{1}{2} \) is \( 2 \).
- The negative reciprocal is \( -2 \), which becomes the slope of the perpendicular line.
Equation of a Line
Determining the equation of a line is a fundamental skill in algebra and is essential for understanding linear relationships.
- Equations of lines can be written in various forms, but the point-slope form is commonly used when you know a point on the line and the slope.
- \( m \) is the slope of the line.
- \( (x_1, y_1) \) is a specific point on the line.
- \( y - 4 = -2(x - 0) \)
- This simplifies further to \( y = -2x + 4 \).