Chapter 9: Problem 7
In Exercises \(7-24,\) find the general form of the equation of the line satisfying the conditions given and graph the line. Through \((3,-1)\) with slope \(-2\)
Short Answer
Expert verified
\(y = -2x + 5\)
Step by step solution
01
- Identify the Point-Slope Form
The point-slope form of the equation of a line is given by \( y - y_1 = m(x - x_1) \), where \((x_1, y_1)\) is a point on the line and \(m\) is the slope.
02
- Substitute the Given Values
Substitute the point \((3, -1)\) into the point-slope form: \( y - (-1) = -2(x - 3) \).
03
- Simplify the Equation
Simplify the equation from Step 2: \[ y + 1 = -2(x - 3) \] \[ y + 1 = -2x + 6 \].
04
- Convert to General Form
Subtract 1 from both sides to get the general form: \[ y = -2x + 5 \].
05
- Graph the Line
Plot the point \((3, -1)\) or use the slope to find another point. Slope \(-2\) means go down 2 units and right 1 unit from \((3, -1)\). Sketch the line through these points.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
General Form of a Line
Understanding the general form of a line is essential in algebra. A linear equation can be written in the general form, which is \[ Ax + By + C = 0 \] where
* First, isolate terms involving variables on one side.
* Ensure that the equation is in the form \[ y = mx + b \] so you can convert it.
* Move every term to one side to structure it as \[ Ax + By + C = 0 \].
For instance, taking the simplified equation from the solution, \[ y = -2x + 5 \], subtract y and 5 from both sides, resulting in \[ 2x + y - 5 = 0 \].
This final form is beneficial for graphing and solving systems of equations, making it a foundational concept you’ll use often in algebra.
- A, B, and C are real numbers.
- A and B are not both zero.
- x and y are variables representing coordinates on the Cartesian plane.
* First, isolate terms involving variables on one side.
* Ensure that the equation is in the form \[ y = mx + b \] so you can convert it.
* Move every term to one side to structure it as \[ Ax + By + C = 0 \].
For instance, taking the simplified equation from the solution, \[ y = -2x + 5 \], subtract y and 5 from both sides, resulting in \[ 2x + y - 5 = 0 \].
This final form is beneficial for graphing and solving systems of equations, making it a foundational concept you’ll use often in algebra.
Slope-Intercept Form
The slope-intercept form of a line is one of the simplest and most common ways to write a linear equation. It is written as \[ y = mx + b \], where:
* Start with the point-slope equation \[ y - y_1 = m(x - x_1) \].
* Isolate y by moving terms around:
**For example:**
- **m** is the slope of the line, showing the steepness or incline.
- **b** is the y-intercept, where the line crosses the y-axis.
* Start with the point-slope equation \[ y - y_1 = m(x - x_1) \].
* Isolate y by moving terms around:
**For example:**
- Substitute the given point and slope: \[ y +1 = -2(x - 3) \].
- Simplify to: \[ y +1 = -2x + 6 \].
- Finally, isolate y: \[ y = -2x + 5 \].
Graphing Linear Equations
Graphing linear equations is a crucial skill in algebra, helping visualize the relationship between two variables. To graph without any step-by-step hassle, follow these straightforward steps:
1. **Identify the Slope and Y-Intercept:**
Don't forget to label your axes and plot multiple points for precision. This approach ensures clear understanding and better visualization of algebraic concepts.
1. **Identify the Slope and Y-Intercept:**
- From the slope-intercept form \[ y = mx + b \], identify **m** and **b**.
- Locate **b** on the y-axis. For \[ y = -2x + 5 \], start at (0, 5).
- Slope **m** is the rise over run. A slope of -2 means go down 2 units for every 1 unit right. From (0, 5), move to (1, 3). Repeat for accuracy.
- Connect the points with a straight line. Extend it across the graph.
Don't forget to label your axes and plot multiple points for precision. This approach ensures clear understanding and better visualization of algebraic concepts.