Chapter 10: Problem 50
Graph the line with the given equation. \(y+2=-2(x-1)\)
Short Answer
Expert verified
The line is graphed with a slope of \(-2\) and a y-intercept of 0, passing through points (0,0) and (1,-2).
Step by step solution
01
Simplify the Equation
Start by simplifying the given equation into the slope-intercept form \(y = mx + b\). We have:\[ y + 2 = -2(x - 1) \]First, distribute the \(-2\):\[ y + 2 = -2x + 2 \]Next, subtract \(2\) from both sides to isolate \(y\):\[ y = -2x + 2 - 2 \]\[ y = -2x \]The equation of the line is now in the form \(y = -2x\).
02
Identify Slope and Y-Intercept
From the simplified equation, \(y = -2x\), we can identify that the slope \(m\) is \(-2\) and the y-intercept \(b\) is \(0\). This means the line crosses the y-axis at the origin (0,0).
03
Plot the Y-Intercept
Begin plotting the graph by drawing a point at the y-intercept. In this case, the y-intercept is at the origin (0,0).
04
Use the Slope to Find Another Point
Using the slope \(-2\), which means that for every 1 unit you move to the right (positive x-direction), you move 2 units down (negative y-direction), find another point. From the origin (0,0), move 1 unit right to (1,0) and then 2 units down to (1,-2). Plot this point.
05
Draw the Line
Use a ruler to draw a straight line through the points (0,0) and (1,-2). This line is the graph of the equation \(y = -2x\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
The slope-intercept form is a way to write the equation of a straight line. It's one of the most common forms and is handy for graphing linear equations.
The general formula for the slope-intercept form is\[ y = mx + b \] where:
The general formula for the slope-intercept form is\[ y = mx + b \] where:
- \(m\) is the slope of the line
- \(b\) is the y-intercept, which is the point where the line crosses the y-axis.
Slope
The slope of a line is a number that describes both the direction and the steepness of the line. In the equation \(y = mx + b\), the slope is represented by the letter \(m\).
- If the slope is positive, the line goes uphill (from left to right).
- If the slope is negative, the line goes downhill.
- A larger absolute value of the slope indicates a steeper line.
- Zero slope means the line is horizontal.
Y-Intercept
The y-intercept of a line is the point where the line crosses the y-axis. In the slope-intercept form \(y = mx + b\), the \(b\) value represents the y-intercept.
- If \(b = 0\), the line crosses the origin (0,0).
- The y-intercept is crucial for starting the graph, as it gives you the initial point on the graph.
- It shows where the line cuts through the y-axis when the value of \(x\) is zero.
Plotting Points
Plotting points is the final step in graphing a linear equation once you have identified the slope and y-intercept. Starting with the y-intercept, you mark it on the y-axis, which gives you your first point.
- Utilize the slope to determine your next point. For example, with a slope of \(-2\), begin at the y-intercept and move horizontally (right if positive direction, left if negative) one unit, then vertically (up if positive slope, down if negative) to locate a second point.
- Once you have two points, you can draw a line through them to complete the graph.