Chapter 3: Problem 232
In the following exercises, find the equation of each line. Write the equation in slope-intercept form. Containing the points (-5,-3) and (4,-6)
Short Answer
Expert verified
\[y = -\frac{1}{3}x - \frac{14}{3}\]
Step by step solution
01
- Find the slope (m)
Use the slope formula to find the slope of the line passing through the points (-5, -3) and (4, -6). The slope formula is: \[m = \frac{y_2 - y_1}{x_2 - x_1}\]Substitute the given points into the formula: \[m = \frac{-6 - (-3)}{4 - (-5)} = \frac{-6 + 3}{4 + 5} = \frac{-3}{9} = -\frac{1}{3}\]
02
- Use the point-slope form
The point-slope form of a line is: \[y - y_1 = m(x - x_1)\]Choose one of the given points, say (-5, -3), and substitute \(x_1 = -5\), \(y_1 = -3\), and \(m = -\frac{1}{3}\) into the point-slope form equation: \[y - (-3) = -\frac{1}{3}(x - (-5))\] \[y + 3 = -\frac{1}{3}(x + 5)\]
03
- Simplify to find the equation
Distribute \(-\frac{1}{3}\) and simplify the equation to get it into slope-intercept form. \[y + 3 = -\frac{1}{3}x - \frac{1}{3}(5)\] \[y + 3 = -\frac{1}{3}x - \frac{5}{3}\] Subtract 3 from both sides to isolate \(y\): \[y = -\frac{1}{3}x - \frac{5}{3} - 3\] Combine the constants: \[y = -\frac{1}{3}x - \frac{5}{3} - \frac{9}{3}\] \[y = -\frac{1}{3}x - \frac{14}{3}\]
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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 of a linear equation is widely used because it lets us easily see both the slope and y-intercept of the line. The general formula is: \[ y = mx + b \] Here,
- \( m \) represents the slope of the line, which is how steep the line is.
- \( b \) represents the y-intercept, which is the point where the line crosses the y-axis.
slope formula
The slope formula helps you determine the steepness or incline of a line between two points. The formula is:
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
To find the slope, you subtract the y-coordinate of the first point \(y_1\) from the y-coordinate of the second point \(y_2\), and divide it by the difference between the x-coordinates \(x_1\) and \(x_2\).
The slope tells you how much y changes for a unit change in x. For the points (-5, -3) and (4, -6), substituting the values gives: \[ m = \frac{-6 - (-3)}{4 - (-5)} = \frac{-3}{9} = -\frac{1}{3} \] The negative sign indicates the line slopes downwards as it moves from left to right.
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
To find the slope, you subtract the y-coordinate of the first point \(y_1\) from the y-coordinate of the second point \(y_2\), and divide it by the difference between the x-coordinates \(x_1\) and \(x_2\).
The slope tells you how much y changes for a unit change in x. For the points (-5, -3) and (4, -6), substituting the values gives: \[ m = \frac{-6 - (-3)}{4 - (-5)} = \frac{-3}{9} = -\frac{1}{3} \] The negative sign indicates the line slopes downwards as it moves from left to right.
point-slope form
Point-slope form is another way to write the equation of a line. It is particularly useful when you know one point on the line and the slope. The formula is: \[ y - y_1 = m(x - x_1) \] Here,
- \( y_1 \) and \( x_1 \) are the coordinates of a known point on the line
- \( m \) is the slope of the line
line equation
To find the final form of the line equation in slope-intercept form from point-slope form, you'll need to simplify: Starting from the point-slope form:
\[ y + 3 = -\frac{1}{3}(x + 5) \]
Distribute \( -\frac{1}{3} \): \[ y + 3 = -\frac{1}{3}x - \frac{5}{3} \]
To isolate \( y \), subtract 3 from both sides: \[ y = -\frac{1}{3}x - \frac{5}{3} - 3 \] Combine constants: \[ y = -\frac{1}{3}x - \frac{14}{3} \] This is the slope-intercept form of the equation passing through the points (-5, -3) and (4, -6). The line equation helps us graph lines and understand how changes in one variable affect the other.
\[ y + 3 = -\frac{1}{3}(x + 5) \]
Distribute \( -\frac{1}{3} \): \[ y + 3 = -\frac{1}{3}x - \frac{5}{3} \]
To isolate \( y \), subtract 3 from both sides: \[ y = -\frac{1}{3}x - \frac{5}{3} - 3 \] Combine constants: \[ y = -\frac{1}{3}x - \frac{14}{3} \] This is the slope-intercept form of the equation passing through the points (-5, -3) and (4, -6). The line equation helps us graph lines and understand how changes in one variable affect the other.