Chapter 3: Problem 79
Find a function whose graph is the given curve. The line segment joining the points \((-2,1)\) and \((4,-6)\)
Short Answer
Expert verified
The function is \( y = -\frac{7}{6}x - \frac{4}{3} \).
Step by step solution
01
Understand the Problem
We are asked to find a function that represents the line between the two points \((-2, 1)\) and \((4, -6)\). A line can be represented by a linear equation, often in the form \(y = mx + c\), where \(m\) is the slope and \(c\) is the y-intercept.
02
Calculate the Slope (m)
The slope \(m\) of the line can be calculated using the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\). For our points, this becomes \(m = \frac{-6 - 1}{4 - (-2)} = \frac{-7}{6}\). Thus, the slope of our line is \(-\frac{7}{6}\).
03
Write the Equation in Point-Slope Form
Using the slope \(-\frac{7}{6}\) and starting from either of the points, let's choose \((-2, 1)\), use the point-slope form \(y - y_1 = m(x - x_1)\). Plug in the values: \(y - 1 = -\frac{7}{6}(x + 2)\).
04
Simplify to Slope-Intercept Form
Distribute and simplify the equation: \(y - 1 = -\frac{7}{6}x - \frac{14}{6}\). Simplifying gives \(y = -\frac{7}{6}x - \frac{7}{3} + 1\). Combine the constants: \(y = -\frac{7}{6}x -\frac{7}{3} + \frac{3}{3}\), which simplifies to \(y = -\frac{7}{6}x -\frac{4}{3}\).
05
Verify the Equation
Check if both points satisfy the equation \(y = -\frac{7}{6}x -\frac{4}{3}\). For \(x = -2\), \(y = -\frac{7}{6}(-2) - \frac{4}{3} = 1\), and for \(x = 4\), \(y = -\frac{7}{6}(4) - \frac{4}{3} = -6\). Thus, both points satisfy the equation, confirming its correctness.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Calculation
In order to determine the equation of a line, it is essential first to calculate the slope. The slope tells us how steep the line is and its direction. We calculate the slope using the formula: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] where
- \((x_1, y_1)\) and \((x_2, y_2)\) are coordinates from two distinct points on the line.
- \( m \) is the slope.
Point-Slope Form
Once the slope is calculated, a linear equation can initially be represented using the point-slope form. This is particularly useful when you know a point on the line and the slope. The point-slope formula is:\[ y - y_1 = m(x - x_1) \]
- \( (x_1, y_1) \) is a point on the line.
- \( m \) is the slope.
Slope-Intercept Form
To simplify the equation further, you can convert it into the slope-intercept form, which is easier to use for graphing. The slope-intercept form is:\[ y = mx + c \]where
- \( m \) is again the slope
- \( c \) is the y-intercept where the line crosses the y-axis.
Graphing a Line
When you need to graph a line from its equation, understanding the slope-intercept form is handy. With the equation \[ y = -\frac{7}{6}x - \frac{4}{3} \]
- The line crosses the y-axis at \( -\frac{4}{3} \).
- The slope \(-\frac{7}{6}\) tells us the line goes down 7 units for every 6 units it goes right.
- Start at the y-intercept, \(-\frac{4}{3}\).
- From there, apply the slope. Go down 7 units and right 6 units to locate another point.
- Draw a line through these points extending in both directions.