Chapter 1: Problem 4
Sketch the line that passes through point (-2,5) and that rises 7 units for every 2 units of left-to-right motion.
Short Answer
Expert verified
The line through (-2,5) with a slope of \(\frac{7}{2}\) is \(y = \frac{7}{2}x + 12\).
Step by step solution
01
Determine the slope
The slope of a line is a measure of how steep the line is. In this exercise, the line rises 7 units for every 2 units of horizontal motion. This means the slope \( m = \frac{7}{2} \), as slope is calculated by rise over run.
02
Write the point-slope form of the line
We utilize the point-slope form of a line equation, \( y - y_1 = m(x - x_1) \), where \((x_1, y_1)\) is a point the line passes through and \( m \) is the slope. Here, the line passes through \((-2, 5)\), so \(x_1 = -2\) and \(y_1 = 5\). Substituting these values, we have: \( y - 5 = \frac{7}{2}(x + 2) \).
03
Simplify the equation
To make the equation easier to graph, convert it into the slope-intercept form \( y = mx + b \). Start by distributing: \( y - 5 = \frac{7}{2}x + 7 \). Add 5 to both sides to solve for \( y \): \( y = \frac{7}{2}x + 12 \).
04
Sketch the line
Using the slope-intercept form \( y = \frac{7}{2}x + 12 \), identify the y-intercept \( b = 12 \), where the line crosses the y-axis. From the point \((0, 12)\), use the slope \( \frac{7}{2} \) to find another point by moving 2 units right and 7 units up, ending at \((2, 19)\). Connect these points to draw the line. Note, the original point \((-2, 5)\) should also be on this line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Point-Slope Form
The point-slope form is a powerful way to write the equation of a line when you know a point on the line and the slope. It's particularly useful in situations where you only have partial information about the line, like in this exercise where the line goes through a specific point and has a known slope.
Effectively, the point-slope form is written as: \[ y - y_1 = m(x - x_1) \] Where
Effectively, the point-slope form is written as: \[ y - y_1 = m(x - x_1) \] Where
- \((x_1, y_1)\) is a given point on the line
- \(m\) is the slope of the line.
Line Through a Point
Understanding how to find a line through a point is crucial for working with linear equations. In mathematics, a line can be precisely described if you have a point that it passes through and its slope. Imagine you want to draw a line on a graph. It leaves the starting point, like the one at \((-2, 5)\), and follows the direction determined by the slope.
The slope, which is the rate of change as you move along the line, helps establish how steep the line is. With a slope of \(\frac{7}{2}\), this means for every 2 units you move horizontally (either to the left or right), you rise or fall 7 units vertically.
Creating the equation of a line using these tidbits of information not only anchors the line in place but also sets its direction, like tracing a path through a forest by always moving in the same direction as a compass.
The slope, which is the rate of change as you move along the line, helps establish how steep the line is. With a slope of \(\frac{7}{2}\), this means for every 2 units you move horizontally (either to the left or right), you rise or fall 7 units vertically.
Creating the equation of a line using these tidbits of information not only anchors the line in place but also sets its direction, like tracing a path through a forest by always moving in the same direction as a compass.
Graphing Linear Equations
Graphing linear equations reveals the visual representation of mathematical relationships. A linear equation typically forms a straight line when plotted on a graph. Here's how to sketch a line using the slope-intercept form:
- First, identify the y-intercept from the line equation, where the line crosses the y-axis. In our example, the line given as \( y = \frac{7}{2}x + 12 \) means the y-intercept is 12.
- Begin by plotting this point (0, 12) on the graph.
- Next, use the slope \(\frac{7}{2}\). Starting from your first point, move 2 units right (horizontal movement) and 7 units up (vertical rise) to determine another point, like (2, 19).
- With these two points plotted, draw a straight line through them.
- Ensure previously given points on the line, like (-2, 5), also align perfectly with it.