Chapter 1: Problem 5
Give the (a) \(x\) -intercept, (b) \(y\) -intercept, (c) domain, (d) range, and (e) slope of the line. Do not use a calculator. $$f(x)=-\frac{2}{5} x+2$$
Short Answer
Expert verified
The x-intercept is 5, the y-intercept is 2, the domain is all real numbers, the range is all real numbers, and the slope is -2/5.
Step by step solution
01
Identify the x-intercept
To find the x-intercept, we set \( f(x) = 0 \) and solve for \( x \). \[ 0 = -\frac{2}{5}x + 2 \]Add \( \frac{2}{5}x \) to both sides:\[ \frac{2}{5}x = 2 \]Multiply both sides by \( \frac{5}{2} \) to solve for \( x \):\[ x = 5 \times \frac{2}{2} = 5 \]Thus, the \( x \)-intercept is \( x = 5 \).
02
Identify the y-intercept
To find the y-intercept, we set \( x = 0 \) in \( f(x) \):\[ f(0) = -\frac{2}{5}(0) + 2 = 2 \]This means the \( y \)-intercept is \( y = 2 \).
03
Determine the Domain
The function \( f(x) = -\frac{2}{5}x + 2 \) is a linear function, which means it is defined for all real numbers. Thus, the domain is all real numbers: \((-fty, fty)\).
04
Determine the Range
Since the function \( f(x) = -\frac{2}{5}x + 2 \) is linear and doesn't have restrictions, its range is also all real numbers: \((-fty, fty)\).
05
Find the Slope
The slope of a linear function, given in the form \( f(x) = mx + b \), is the coefficient of \( x \). For this function, \( m = -\frac{2}{5} \). This means the slope is \(-\frac{2}{5}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
x-intercept
To find the x-intercept of a linear function like \( f(x) = -\frac{2}{5} x + 2 \), set \( f(x) \) equal to zero and solve for \( x \). The x-intercept is where the line crosses the x-axis. In this position, the value of \( y \) or \( f(x) \) is zero.
Begin by writing the equation:
Begin by writing the equation:
- \( 0 = -\frac{2}{5} x + 2 \)
- Add \( \frac{2}{5} x \) to both sides to isolate terms involving \( x \): \( \frac{2}{5} x = 2 \)
- \( x = 5 \)
y-intercept
Finding the y-intercept involves setting \( x = 0 \) and solving for \( f(x) \), which is essentially the \( y \)-value where the line crosses the y-axis. It is a straightforward calculation. Plug \( x = 0 \) into the function:
- \[ f(0) = -\frac{2}{5}(0) + 2 = 2 \]
domain and range
In a linear function like \( f(x) = -\frac{2}{5}x + 2 \), the domain and range are simple to identify, since linear functions are not restricted. The domain of a function refers to the set of possible input values (x-values), and the range is the set of possible output values (y-values). For most standard straight lines, both the domain and the range are all real numbers.
- Domain: All real numbers
- Range: All real numbers
- \((-\infty, \infty)\)
slope
The slope of a linear function is a measure of its steepness and direction, and is denoted by \( m \) in the slope-intercept form \( f(x) = mx + b \). It signifies how much \( y \) changes for a given change in \( x \).
For the function \( f(x) = -\frac{2}{5}x + 2 \),
For the function \( f(x) = -\frac{2}{5}x + 2 \),
- the slope \( m \) is \(-\frac{2}{5} \)
- A positive slope indicates a line rising,
- while a negative slope shows a line falling.
- A larger absolute value of the slope means a steeper line.