Chapter 13: Problem 31
What word best describes the function $$ f(x)=-\frac{4}{13} x-\frac{7}{5} ? $$ A. negative B. increasing C. linear D. symmetric
Short Answer
Expert verified
Linear
Step by step solution
01
- Understand the Problem
The function given is a mathematical expression of the form \( f(x) = ax + b \). Identify the type and characteristics of this function.
02
- Identify the Form of the Function
The function \( f(x) = -\frac{4}{13} x - \frac{7}{5} \) is in the form of \( f(x) = ax + b \), which is a linear function. In a linear function, the highest power of \( x \) is 1.
03
- Determine the Characteristics of Linear Functions
Linear functions have a constant rate of change. This means that for any value of \( x \), the function's rate of change is characterized by the coefficient of \( x \). Thus, the function is linear and not quadratic, cubic, or another higher-order polynomial.
04
- Compare with Choices
The choices are: A. Negative, B. Increasing, C. Linear, D. Symmetric. The term that best fits a function of the form \( f(x) = ax + b \) is 'linear'. It is not inherently negative, increasing, or symmetric based solely on its general form.
05
- Conclusion
After understanding that the given function is a straight line (has a linear form\( f(x) = -\frac{4}{13} x - \frac{7}{5} \)), we can determine that the best word to describe it is 'linear'.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rate of change
In linear functions, the 'rate of change' is a critical concept. It tells us how much one quantity changes for a unit change in another quantity. For the linear function \( f(x) = -\frac{4}{13} x - \frac{7}{5} \), the rate of change is represented by the coefficient of \( x \), which is \( -\frac{4}{13} \).
This coefficient indicates how rapidly the value of \( f(x) \) changes as \( x \) increases. We interpret this as:
This coefficient indicates how rapidly the value of \( f(x) \) changes as \( x \) increases. We interpret this as:
- A negative coefficient \( (-\frac{4}{13}) \) means that \( f(x) \) decreases as \( x \) increases.
- The magnitude, \( \frac{4}{13} \), shows how steep the decline is.
Constant rate
Linear functions are defined by their 'constant rate' of change. This means that for every unit increase in \( x \), there is a consistent change in \( f(x) \). For example, in our function \( f(x) = -\frac{4}{13} x - \frac{7}{5} \), the rate of change does not vary; it is always \( -\frac{4}{13} \). This constancy has several implications:
- Graphically, it results in a straight line.
- In practical problems, it represents predictable and uniform changes.
Mathematical expressions
Linear functions are represented by simple 'mathematical expressions' of the form \( ax + b \). In our case, the expression is: \( f(x) = -\frac{4}{13} x - \frac{7}{5} \). Here’s a breakdown of the components:
- \( a \) (\( -\frac{4}{13} \)): The slope. It determines the direction (positive/negative) and steepness.
- \( b \) (\( -\frac{7}{5} \)): The y-intercept. It’s the value of \( f(x) \) when \( x \) is zero.