Chapter 5: Problem 27
Sketch the graph of the function and check the graph with a graphing calculator. Describe how each graph can be obtained from the graph of a basic exponential function.. $$f(x)=2^{x+1}$$
Short Answer
Expert verified
Shift the graph of \( y = 2^x \) 1 unit to the left.
Step by step solution
01
- Identify the Basic Function
The basic function is an exponential function of the form \( f(x) = a^x \). In this problem, the base of the exponential function is 2. So the basic function is \( f(x) = 2^x \).
02
- Understand the Transformation
The function given is \( f(x) = 2^{x+1} \). This indicates a horizontal shift of the basic function \( f(x) = 2^x \). Specifically, the \(x+1\) inside the exponent will shift the graph to the left by 1 unit.
03
- Sketch the Basic Exponential Function
First, sketch the graph of the basic exponential function \( y = 2^x \). This graph passes through the points (0, 1), (1, 2), and (-1, 0.5), and it increases rapidly.
04
- Apply the Transformation
Since the function is \( f(x) = 2^{x+1} \), shift the graph of \( y = 2^x \) 1 unit to the left. This means each point \((x, y)\) on the graph of \( y = 2^x \) is transformed to \((x-1, y)\).
05
- Check With a Graphing Calculator
Use a graphing calculator to input \( f(x) = 2^{x+1} \). Compare the calculator's graph with your hand-drawn graph to ensure accuracy. Both should show the graph shifted left by 1 unit.
06
- Describe the Transformation
The graph of \( f(x) = 2^{x+1} \) can be obtained by shifting the graph of the basic exponential function \( y = 2^x \) to the left by 1 unit.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Basic Exponential Function
An exponential function is a mathematical expression where a constant base is raised to a variable exponent, generally represented as \( f(x) = a^x \). In this basic form, the function grows (or decays) rapidly:
- Passes through the point (0, 1), since any number to the power of 0 is 1.
- For bases greater than 1 (e.g., \( a = 2 \)), the function grows exponentially as \( x \) increases.
- For bases between 0 and 1, the function decays exponentially.
- Passes through the point (0, 1), since any number to the power of 0 is 1.
- Includes points like (1, 2) and (-1, 0.5), representing rapid growth and decay respectively.
- The graph has a horizontal asymptote at \( y = 0 \); it approaches zero but never touches it.
Horizontal Shift
A horizontal shift moves the graph left or right along the x-axis. For the function \( f(x) = 2^{x+1} \), the expression \( x+1 \) signifies that we shift the graph to the left by 1 unit. Why the move to the left? In general:
- Take the basic exponential function \( y = 2^x \) which passes through (0, 1), (1, 2), and (-1, 0.5).
- When the exponent has a positive constant added (\( x + k \)), we shift left by \( k \) units.
- If the exponent has a negative constant added (\( x - k \)), we shift right by \( k \) units.
- Take the basic exponential function \( y = 2^x \) which passes through (0, 1), (1, 2), and (-1, 0.5).
- To shift left 1 unit, subtract 1 from each x-coordinate.
- New points become (-1, 1), (0, 2), and (-2, 0.5), reflecting the leftward shift.
Graph Transformation
Graph transformation applies when you need to modify the base graph to match a transformed function. Steps to transform \( y = 2^x \) into \( f(x) = 2^{x+1} \):
1. Start with the graph of \( y = 2^x \).
2. Apply the horizontal shift: Shift each point left by 1 unit (i.e., change (x, y) to (x-1, y)).
Check these points:
Buy Useful Pointers: Practice is key! Try shifting graphs of different exponential functions and observe the transformations. Use graphing tools for a quick visual comparison to reinforce your understanding.
1. Start with the graph of \( y = 2^x \).
2. Apply the horizontal shift: Shift each point left by 1 unit (i.e., change (x, y) to (x-1, y)).
Check these points:
- (0, 1) moves to (-1, 1)
- (1, 2) shifts to (0, 2)
- (-1, 0.5) transforms to (-2, 0.5)
Buy Useful Pointers: Practice is key! Try shifting graphs of different exponential functions and observe the transformations. Use graphing tools for a quick visual comparison to reinforce your understanding.