Chapter 3: Problem 59
Write an equation for each line passing through the given point and having the given slope. Give the final answer in slope-intercept form. See Examples 5 and \(6 .\) $$ (-2,5), m=\frac{2}{3} $$
Short Answer
Expert verified
The equation of the line is \( y = \frac{2}{3}x + \frac{19}{3} \).
Step by step solution
01
- Understand the slope-intercept form
The slope-intercept form of a linear equation is given by \( y = mx + b \), where \( m \) represents the slope and \( b \) represents the y-intercept.
02
- Substitute the slope and point into the slope-intercept form
We know the slope \( m = \frac{2}{3} \) and the point \( (-2, 5) \). Substitute these into the equation. First, write the equation with the slope: \( y = \frac{2}{3}x + b \).
03
- Substitute the point to find the y-intercept
Substitute \( x = -2 \) and \( y = 5 \) into the equation to find \( b \). \( 5 = \frac{2}{3}(-2) + b \) Simplify and solve for \( b \): \( 5 = -\frac{4}{3} + b \).
04
- Solve for the y-intercept
Add \( \frac{4}{3} \) to both sides to isolate \( b \): \( 5 + \frac{4}{3} = b \). Convert \( 5 \) to a fraction: \( \frac{15}{3} + \frac{4}{3} = b \). Simplify: \( \frac{19}{3} = b \).
05
- Write the final equation
Now that we have the slope \( m = \frac{2}{3} \) and the y-intercept \( b = \frac{19}{3} \), substitute them back into the slope-intercept form equation: \( y = \frac{2}{3}x + \frac{19}{3} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Equations
Understanding linear equations is core to tackling many algebra problems. A linear equation is a mathematical expression that creates a straight line when graphed on a coordinate plane. The general form of a linear equation is: \[ y = mx + b \] Here,
- \( y \): represents the dependent variable (usually the y-coordinate).
- \( x \): represents the independent variable (usually the x-coordinate).
- \( m \): represents the slope of the line, which shows the rate of change.
- \( b \): represents the y-intercept, which is the point where the line crosses the y-axis.
Slope
The slope of a line is a measure of its steepness and direction. Mathematically, it's defined as: \[ m = \frac{\Delta y}{\Delta x} \] This means the slope\( m \) is calculated by dividing the change in y (vertical difference) by the change in x (horizontal difference). The slope tells us how much y increases (or decreases) as x increases.
- A positive slope means the line inclines upward as it moves from left to right.
- A negative slope means the line declines downward.
- A zero slope means the line is horizontal.
- An undefined slope means the line is vertical.
Y-Intercept
The y-intercept of a line is where it crosses the y-axis. In the slope-intercept form \[ y = mx + b \]\( b \) is the y-intercept. Determining the y-intercept is straightforward once you have the slope and a point on the line. You can substitute the values into the equation to solve for \( b \). In our problem, we started with the slope \( \frac{2}{3} \) and a point (-2, 5). We substituted these values into the equation to find the y-intercept:
- Step 1: Plug in the point and the slope: \( 5 = \frac{2}{3}(-2) + b \)
- Step 2: Simplify: \( 5 = -\frac{4}{3} + b \)
- Step 3: Solve for \( b \):\( b = \frac{19}{3} \)
Substitution Method
The substitution method is a powerful tool for solving linear equations, especially when working with slope-intercept form. Substitution involves replacing one variable with its actual value to find the unknown terms. In our problem, we knew the slope \( m = \frac{2}{3} \) and the point (-2, 5). Here’s how we used substitution to find the y-intercept:
- Start with the slope-intercept form: \( y = \frac{2}{3}x + b \)
- Substitute the known values (x = -2, y = 5): \( 5 = \frac{2}{3}(-2) + b \)
- Simplify: \( 5 = -\frac{4}{3} + b \)
- Isolate \( b \): \( 5 + \frac{4}{3} = b \)
- Convert 5 to a fraction: \( \frac{15}{3} + \frac{4}{3} = b \)
- Solve \( b \): \( b = \frac{19}{3} \)