Chapter 2: Problem 17
Write an equation in slope-intercept form for the line that satisfies each set of conditions. passes through \((-2,5)\) and \((3,1)\)
Short Answer
Expert verified
\( y = -\frac{4}{5}x + \frac{17}{5} \)
Step by step solution
01
Understand the Slope-Intercept Form
The slope-intercept form of a linear equation is \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. To write the equation, we first need to find the slope and then the y-intercept.
02
Calculate the Slope
The slope \( m \) of a line passing through two points \((x_1, y_1)\) and \((x_2, y_2)\) is calculated using the formula \( m = \frac{y_2-y_1}{x_2-x_1} \). Here, point 1 is \((-2,5)\) and point 2 is \((3,1)\). Thus, \( m = \frac{1-5}{3-(-2)} = \frac{-4}{5} = -\frac{4}{5} \).
03
Identify the Slope-Intercept Equation Form
After finding the slope, use point-slope form \( y - y_1 = m(x - x_1) \) to find the equation. Choose one point, say \((-2,5)\), and substitute it along with the slope: \( y - 5 = -\frac{4}{5}(x + 2) \).
04
Simplify to Slope-Intercept Form
Distribute the slope and simplify to find \( b \). \[ y - 5 = -\frac{4}{5}x - \frac{8}{5} \] Add 5 to both sides to solve for \( y \): \[ y = -\frac{4}{5}x - \frac{8}{5} + 5 \] Convert 5 to a fraction with denominator 5: \[ y = -\frac{4}{5}x - \frac{8}{5} + \frac{25}{5} \] Combine the fractions: \[ y = -\frac{4}{5}x + \frac{17}{5} \] Thus, the slope-intercept form is \( y = -\frac{4}{5}x + \frac{17}{5} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Equations
Linear equations are mathematical expressions that represent straight lines when plotted on a graph. These equations take the form of \( y = mx + b \), where:
- \( y \) is the dependent variable (usually the vertical axis).
- \( x \) is the independent variable (usually the horizontal axis).
- \( m \) represents the slope of the line.
- \( b \) is the y-intercept, where the line crosses the y-axis.
Slope Calculation
Calculating the slope of a line involves determining how steep the line is. The slope is a ratio that describes the change in the vertical direction (rise) compared to the horizontal direction (run).To calculate the slope \( m \) between two points \((x_1, y_1)\) and \((x_2, y_2)\), use the formula:\[m = \frac{y_2 - y_1}{x_2 - x_1}\]This formula finds the difference in the \( y \)-values and the \( x \)-values. It's essential to:
- Identify the correct points as \((x_1, y_1)\) and \((x_2, y_2)\).
- Perform the subtraction correctly to avoid confusion.
Point-Slope Form
The point-slope form of a linear equation, \( y - y_1 = m(x - x_1) \), is a valuable format for creating the equation of a line when you know a point on the line and the slope.It allows you to plug in:
- \( (x_1, y_1) \), a known point on the line.
- \( m \), the slope of the line.
Y-Intercept
The y-intercept is the point where the line crosses the y-axis. In the slope-intercept form \( y = mx + b \), the \( b \) represents the y-intercept. It is crucial because it provides a starting point for graphing a linear equation.To find the y-intercept from the point-slope form:
- Start by expanding the equation and solving for \( y \).
- Move from \( y - y_1 = m(x - x_1) \) to an equation which isolates \( y \).
- Plug in the slope \( m \) and your known point, and simplify accordingly.