Chapter 5: Problem 24
Write an equation of the line satisfying the given conditions. Passing through \((0,-2)\) and \((-2,0)\)
Short Answer
Expert verified
The equation of the line is \ y = -x - 2 \.
Step by step solution
01
Identify the coordinates
The given points are \(0, -2\) and \(-2, 0\). Let's call them \(x_1, y_1\) and \(x_2, y_2\). So, \(x_1 = 0\), \(y_1 = -2\), \(x_2 = -2\), and \(y_2 = 0\).
02
Calculate the slope (m)
Use the slope formula: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] Substituting in the coordinates: \[ m = \frac{0 - (-2)}{-2 - 0} = \frac{2}{-2} = -1 \]
03
Use the point-slope form
Now insert the slope \(m = -1\) and one of the points, let's use \( (0, -2) \), into the point-slope form equation: \[ y - y_1 = m(x - x_1) \] This gives: \[ y - (-2) = -1(x - 0) \]
04
Simplify to slope-intercept form
Simplify this equation to get it into slope-intercept form \(y = mx + b\): \[ y + 2 = -x \] Subtract 2 from both sides to solve for y: \[ y = -x - 2 \]
05
Conclusion
The equation of the line passing through the points \(0,-2\) and \(-2,0\) is \[ y = -x - 2 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
slope
The slope of a line measures its steepness and direction. It is calculated as the change in the y-coordinates divided by the change in the x-coordinates between two points. This ratio tells us how much y changes per unit change in x. The formula for the slope (m) is: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] For the given points (0, -2) and (-2, 0), we calculated: \[ m = \frac{0 - (-2)}{-2 - 0} = \frac{2}{-2} = -1 \] This means the line decreases by 1 unit vertically for every 1 unit it moves horizontally to the right.
point-slope form
The point-slope form of a line's equation is a very convenient way to write the equation when you know the slope and one point on the line. The general formula is: \[ y - y_1 = m(x - x_1) \] In this format,
- (y - y_1) shifts the line vertically by y_1.
- (x - x_1) shifts the line horizontally by x_1.
- The slope (m) is the same as discussed previously.
slope-intercept form
The slope-intercept form of a line's equation is quite popular and easy to use. It looks like this: \[ y = mx + b \] Here, m is the slope of the line, and b is the y-intercept (the point where the line crosses the y-axis). In our example, after converting from the point-slope form, we got: \[ y + 2 = -x \] To convert this into slope-intercept form, subtract 2 from both sides: \[ y = -x - 2 \] This tells us that the slope (m) is -1 and the y-intercept (b) is -2. This means the line crosses the y-axis at -2.
coordinates
Coordinates are used to locate points on the Cartesian plane. They consist of an ordered pair (x, y), where:
- The x-coordinate tells you how far to move left or right from the origin (0, 0).
- The y-coordinate tells you how far to move up or down from the origin.
- (0, -2): Start at the origin, move 0 units left/right (x=0), and 2 units down (y=-2).
- (-2, 0): Start at the origin, move 2 units left (x=-2), and 0 units up/down (y=0).