Chapter 1: Problem 13
Find equations for these lines: a. Slope 5 and \(y\) intercept \((0,-4)\) b. Slope \(-2\) and contains \((1,3)\) c. Contains \((5,4)\) and is parallel to \(2 x+y=3\)
Short Answer
Expert verified
a. \( y = 5x - 4 \)b. \( y = -2x + 5 \)c. \( y = -2x + 14 \)
Step by step solution
01
Identify the equation form
The general equation of a line in slope-intercept form is given by: \( y = mx + b \). Here, \( m \) is the slope and \( b \) is the y-intercept.
02
Equation for part a
Given the slope \( m = 5 \) and the y-intercept \( (0, -4) \), substitute these values into the slope-intercept form: \( y = 5x - 4 \).
03
Identify point-slope form for part b
The point-slope form of a line is given by: \( y - y_1 = m(x - x_1) \). Here, \( m \) is the slope and \( (x_1, y_1) \) is a point on the line.
04
Equation for part b
Given the slope \( m = -2 \) and the point \( (1, 3) \), substitute these values into the point-slope form: \( y - 3 = -2(x - 1) \). Simplify to the slope-intercept form: \( y = -2x + 5 \).
05
Identify parallel line condition for part c
Lines that are parallel have the same slope. The given line is \( 2x + y = 3 \). First, convert this line to slope-intercept form by solving for \( y \): \( y = -2x + 3 \). The slope of this line is \( -2 \).
06
Use point-slope form for part c
Given the point \( (5, 4) \) and the slope \( -2 \), use the point-slope form: \( y - 4 = -2(x - 5) \). Simplify this to slope-intercept form: \( y = -2x + 14 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Equations
Linear equations describe straight lines on a graph. They have no exponents or curves. In their simplest form, you can write them as: \[ y = mx + b \] Here, \( m \) is the slope, which tells you how steep the line is. True to its name, \( x \) always appears in the equation and \( b \) is the y-intercept, showing where the line crosses the y-axis. Simple examples include:
Remember, linear equations can always be transformed into the form \( y = mx + b \). This is very useful and forms the foundation for understanding lines on a graph.
- \( y = 3x + 1 \)
- \( y = 0.5x - 2 \)
- \( y = -x + 4 \)
Remember, linear equations can always be transformed into the form \( y = mx + b \). This is very useful and forms the foundation for understanding lines on a graph.
Slope-Intercept Form
The slope-intercept form is a specific way to write linear equations. It looks like: \[ y = mx + b \]
- \( m \) is the slope
- \( b \) is the y-intercept
- The slope \( m = 5 \), meaning the line goes up 5 units for every 1 unit you go right.
- The y-intercept \( b = -4 \), meaning it crosses the y-axis at -4.
Point-Slope Form
The point-slope form is often used when you know a point on the line and its slope. The form is: \[ y - y_1 = m(x - x_1)\] Here, \( m \) is the slope, and \( (x_1, y_1) \) is a specific point on the line. For example, if the slope is
- -2
- passing through the point (1, 3),
Parallel Lines
Parallel lines are lines that never intersect. They have the same slope but different y-intercepts. For instance, let's determine the equation of a line parallel to \(2x + y = 3\) that passes through (5, 4). First, we convert \(2x + y = 3\) to slope-intercept form: \(y = -2x + 3\). This tells us the slope is -2. Next, using the point-slope form with the given point (5, 4): \( y - 4 = -2(x - 5) \). Simplify this to: \( y = -2x + 14 \). Hence, the line parallel to \(2x + y = 3\) and passing through (5, 4) is \( y = -2x + 14 \). Understanding the concept of parallel lines helps in solving many geometry and algebra problems efficiently.