Chapter 4: Problem 7
Find the linear functions satisfying the given conditions. The graph of the inverse function passes through the points (-1,2) and (0,4)
Short Answer
Expert verified
The linear function is \(y = \frac{1}{2}x - 2\).
Step by step solution
01
Understand the relationship between a function and its inverse
First, note that if a point \((a, b)\) lies on the graph of a function, then \((b, a)\) must lie on the graph of its inverse. The inverse function has its x and y coordinates swapped compared to the original function. Therefore, if points \((-1, 2)\) and \((0, 4)\) lie on the inverse function, then \((2, -1)\) and \((4, 0)\) lie on the original function.
02
Identify the linear function parameters
A linear function can be expressed in the form \(y = mx + c\), where \(m\) is the slope and \(c\) is the y-intercept. We will use the points \((2, -1)\) and \((4, 0)\) to find \(m\) and \(c\).
03
Calculate the slope \(m\)
The slope \(m\) of a line passing through two points \((x_1, y_1)\) and \((x_2, y_2)\) is calculated as: \[m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{0 - (-1)}{4 - 2} = \frac{1}{2}\]
04
Solve for the y-intercept \(c\)
Substitute the slope \(m = \frac{1}{2}\) and one of the points (e.g., (2, -1)) into the linear equation \(y = mx + c\):\[-1 = \frac{1}{2} \cdot 2 + c \]\[-1 = 1 + c \]\[c = -2 \]
05
Form the equation of the linear function
Now that you have both \(m = \frac{1}{2}\) and \(c = -2\), you can write the equation of the linear function:\[y = \frac{1}{2}x - 2\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Functions
Linear functions are fundamental in mathematics and are characterized by their straight-line graphs. These functions can be represented by the equation \( y = mx + c \), where \( m \) is the slope and \( c \) is the y-intercept. Linear functions have the following properties:
- They graph as straight lines.
- The slope \( m \) indicates the steepness of the line. A positive slope means the line goes upwards, while a negative slope means it goes downwards.
- The y-intercept \( c \) is the point where the line crosses the y-axis.
Slope-Intercept Form
The slope-intercept form of a linear equation is one of the most straightforward ways to represent a linear function. The general formulation is \( y = mx + c \). Here, \( m \) denotes the slope, showing how much \( y \) changes for each unit increase in \( x \), and \( c \) is the y-intercept, indicating where the line crosses the y-axis.
Let's break down this form:
Let's break down this form:
- Slope \( (m) \): This value tells us the rate of change of the line. It is calculated as the "rise over run," or the change in \( y \) over the change in \( x \).
- Y-Intercept \( (c) \): This is the initial value of \( y \) when \( x = 0 \). It provides a starting point on the graph for plotting the line.
Point-Slope Formula
The point-slope formula is particularly useful when you know a single point on a line and the line's slope. This formula is an alternative way to write the equation of a linear line. It takes the form \( y - y_1 = m(x - x_1) \), where \( (x_1, y_1) \) is a point on the line and \( m \) is the slope.
This format is beneficial in several scenarios:
This format is beneficial in several scenarios:
- If you need to write the equation of a line quickly when given a point and a slope, this formula is direct and efficient.
- It's helpful for converting between different forms of a linear equation, such as into the slope-intercept form.
- The point-slope form also aids in easily visualizing how a line will behave given changes to its slope or through points.