Chapter 4: Problem 435
Find the equation of a line containing the given points. Write the equation in slope-intercept form. (-2,8) and (-4,-6)
Short Answer
Expert verified
y = 7x + 22
Step by step solution
01
- Identify the Coordinates
Identify the coordinates of the given points. The given points are (-2, 8) and (-4, -6).
02
- Calculate the Slope
Use the formula for the slope of a line passing through two points: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] Substitute the coordinates of the points (-2, 8) and (-4, -6): \[ m = \frac{-6 - 8}{-4 - (-2)} = \frac{-14}{-2} = 7 \] Hence, the slope (\text{m}) is 7.
03
- Use the Point-Slope Form
Use the point-slope form of the equation of a line:\[ y - y_1 = m(x - x_1) \] Choose one of the given points (-2, 8) and substitute it into the formula: \[ y - 8 = 7(x + 2) \]
04
- Simplify to Slope-Intercept Form
Simplify the equation into the slope-intercept form (\text{y = mx + b}): \[ y - 8 = 7(x + 2) \] Distribute the 7: \[ y - 8 = 7x + 14 \] Add 8 to both sides: \[ y = 7x + 22 \] Therefore, the equation of the line in slope-intercept form is y = 7x + 22.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Equation of a Line
An equation of a line represents all the points that lie on that line. Typically, we use the slope-intercept form of the equation:y = mx + bHere:
- y stands for the y-coordinate of any point on the line.
- m represents the slope (steepness) of the line.
- x is the x-coordinate of any point on the line.
- b is the y-intercept, where the line crosses the y-axis.
Slope Calculation
The slope of a line measures its steepness. A positive slope means the line rises as it goes from left to right, while a negative slope means it falls. To find the slope between two points y_1 and y_2 with coordinates (x_1, y_1) and (x_2, y_2), we use the formula: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \]In our example, the points are (-2, 8) and (-4, -6). Plugging in these coordinates, we get:\[ m = \frac{-6 - 8}{-4 - (-2)} = \frac{-14}{-2} = 7 \]Thus, the slope is 7, meaning the line rises steeply upwards.
Point-Slope Form
The point-slope form of a line's equation is useful for quickly forming the equation when you know a point and the slope. It looks like this: \[ y - y_1 = m(x - x_1) \]Here:
- m is the slope.
- (x_1, y_1) is a known point on the line.
Coordinate Geometry
Coordinate geometry, or analytic geometry, bridges algebra and geometry using coordinates. By plotting points, lines, and curves on an x-y plane, we can solve geometric problems algebraically.to understand why coordinate geometry is powerful:
- It allows for precise plotting and measuring of geometric forms.
- It simplifies complex problems into manageable algebraic equations.
- You can visually see the relationship between equations and their graphical counterparts.