Chapter 2: Problem 4
Find the point-slope form of the line passing through the given points. Use the first point as \(\left(x_{1}, y_{1}\right) .\) Plot the points and graph the line by hand. $$ (-1,2),(-2,-3) $$
Short Answer
Expert verified
The point-slope form is \( y - 2 = 5(x + 1) \).
Step by step solution
01
Calculate the Slope
The first step is to find the slope of the line that passes through the given points \((-1, 2)\) and \((-2, -3)\). The formula for the slope (\(m\)) between two points \( (x_1, y_1) \) and \( (x_2, y_2) \) is:\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]Plugging in the coordinates of the points, we have:\[ m = \frac{-3 - 2}{-2 + 1} = \frac{-5}{-1} = 5 \]So the slope \(m\) is 5.
02
Write the Point-Slope Form Equation
Next, we use the point-slope form of a line equation, which is:\[ y - y_1 = m(x - x_1) \]Here, \(x_1, y_1\) is the first point \((-1, 2)\) and the slope \(m\) is 5. Plug these into the formula:\[ y - 2 = 5(x + 1). \]This equation represents the line in point-slope form.
03
Verify by Plotting the Points
To ensure the equation is correct, plot the two points \((-1, 2)\) and \((-2, -3)\) on a graph. Then, from the point \((-1, 2)\), use the slope \(5\) to rise 5 units and run 1 unit to the right to find another point on the line. Continue checking multiple points if necessary. These plots should fall on a straight line following the equation, confirming the accuracy.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Calculation
Understanding how to calculate the slope of a line is crucial in mathematics. The slope essentially measures how steep a line is. This is a key concept when determining the relationship between two points on a line. Given two points, you can find the slope using the formula:\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]Here, \(x_1, y_1\) and \(x_2, y_2\) are the coordinates of the two points. The slope \(m\) tells us how much \(y\) changes when \(x\) increases by one unit.
- A positive slope means the line ascends from left to right.
- A negative slope indicates the line descends from left to right.
- If the slope is zero, the line is horizontal.
- An undefined slope suggests a vertical line.
Graphing Lines
Graphing lines involves visually representing them on a coordinate plane based on their mathematical equation. One efficient way to graph a line is to use its slope and intercepts. However, when given the point-slope form, you can start from a known point and use the slope to find additional points.
To graph using a line's slope:
To graph using a line's slope:
- Start at a known point, like \((-1, 2)\).
- From there, use the slope to find subsequent points. If the slope is 5, move up 5 units and to the right 1 unit to plot the next point.
Two-Point Formula
The two-point formula is instrumental in creating the equation of a line from two specific points. It involves calculating the slope as the first step, followed by plugging it into the point-slope form of the line equation.
Here's a recap of the important steps:
Here's a recap of the important steps:
- Calculate the slope \(m\) using the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\).
- Choose one of the points to serve as \(x_1, y_1\).
- Use the point-slope form: \(y - y_1 = m(x - x_1)\) to create the line's equation.
Plotting Points
Plotting points accurately on a graph is foundational for visualizing equations and understanding geometric relationships. Each point on a graph is represented by an \(x, y\) pair on the coordinate plane.
Let's break down the process of plotting:
Repeat the process for the other point \((-2, -3)\), moving left 2 units and down 3 units. Accurate plotting keeps the graph true to the line's equation and reflects it correctly in visual representation.
Let's break down the process of plotting:
- Identify the \(x\) (horizontal) and \(y\) (vertical) coordinates.
- Start from the origin, \(0,0\), and move horizontally to \(x\).
- Next, move vertically to \(y\).
- Mark the point clearly on the graph.
Repeat the process for the other point \((-2, -3)\), moving left 2 units and down 3 units. Accurate plotting keeps the graph true to the line's equation and reflects it correctly in visual representation.