Chapter 6: Problem 46
Use transformations to graph each function. Determine the domain, range, horizontal asymptote, and y-intercept of each function. $$ f(x)=3^{x}-2 $$
Short Answer
Expert verified
Domain: (-∞, ∞), Range: (-2, ∞), Horizontal Asymptote: y = -2, Y-intercept: (0, -1)
Step by step solution
01
- Identify the Base Function
Identify the base exponential function. The base function for the given equation is 3^x.
02
- Vertical Shift
Recognize and apply the vertical shift. The function f(x) has a vertical shift of -2. This means the graph of 3^x is shifted downward by 2 units.
03
- Horizontal Asymptote
Determine the horizontal asymptote. For the function f(x) = 3^x - 2, the horizontal asymptote is y = -2.
04
- Y-intercept
Find the y-intercept by substituting x = 0 into the function. So, f(0) = 3^0 - 2, which simplifies to 1 - 2 = -1. Therefore, the y-intercept is (0, -1).
05
- Domain
The domain of an exponential function is all real numbers. Therefore, the domain of f(x) = 3^x - 2 is (-∞, ∞).
06
- Range
Determine the range of the function. Since the graph of 3^x is shifted downward by 2 units, the range is all real numbers greater than -2. Therefore, the range is (-2, ∞).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
exponential function
An exponential function is a type of function where the variable is an exponent. These functions have the form \( f(x) = a \times b^x \, \text{or} \, f(x) = b^x \), where \(a\) and \(b\) are constants. In the context of the given function \( f(x) = 3^x - 2 \), the base function is \(3^x\). This means our exponential function will grow as \(x\) increases, rapidly rising towards positive infinity.
Key points to remember about exponential functions:
Key points to remember about exponential functions:
- They are not linear; they grow or decay at an increasing rate.
- When the base \(b > 1\), the function represents growth.
- For \(b < 1\) (but \(b > 0\)), the function represents decay.
- The graph always passes through the point (0,1) if there is no vertical shift.
vertical shift
A vertical shift occurs when the entire graph of the function is moved up or down along the y-axis. In our function \(f(x) = 3^x - 2\), there is a vertical shift of -2. This means the graph of the base function \(3^x\) is shifted downward by 2 units.
Here's what you need to know about vertical shifts:
Here's what you need to know about vertical shifts:
- If the transformation is \( f(x) = g(x) + k \), where \(k > 0\), the graph shifts upwards.
- For \( f(x) = g(x) - k \), where \(k > 0\), the graph shifts downwards.
- This vertical shift impacts the y-intercept and the horizontal asymptote.
horizontal asymptote
A horizontal asymptote is a horizontal line that the graph of a function approaches but never actually touches as \( x \) goes to positive or negative infinity. For the function \(f(x) = 3^x - 2\), the horizontal asymptote is \( y = -2 \).
Important points about horizontal asymptotes:
Important points about horizontal asymptotes:
- They indicate the behavior of the function at extreme values of \( x \).
- For \(f(x) = 3^x - 2\), the base function \(3^x\) normally approaches \( y = 0 \). The subtraction of 2 shifts this asymptote down to \( y = -2 \).
- This line helps in understanding the limiting value of the function as \( x \) grows very large or very small.
domain and range
The domain of a function describes all the possible input values (\(x\)) that the function can accept, while the range describes all possible output values (\(y\)).
Let's explore the domain and range for \(f(x) = 3^x - 2\):
Let's explore the domain and range for \(f(x) = 3^x - 2\):
- **Domain:** Exponential functions typically accept all real numbers for \(x\). So, the domain of \(f(x)\) is \(( -∞, ∞ )\).
- **Range:** To determine the range, consider the vertical shift. The base function \(3^x\) has a range of \(( 0, ∞ )\), but shifting it down by 2 units changes the range. Thus, the range of \(f(x) = 3^x - 2\) is \(( -2, ∞ )\).