Chapter 12: Problem 10
Graph each exponential function. $$ y=-3^{x} $$
Short Answer
Expert verified
Graph reflects across x-axis and shows exponential decay.
Step by step solution
01
Identify the Base Function
The base function here is an exponential function of the form \( y = a^x \), where \( a = 3 \). This indicates that the basic form of the function is exponential growth by a factor of 3 for every increase in \( x \).
02
Recognize the Transformation
In the given function \( y = -3^x \), the negative sign in front of \( 3^x \) indicates a reflection across the x-axis. This means instead of growing upwards as \( x \) increases, the function will decrease.
03
Create a Table of Values
Choose a few values of \( x \) to substitute into the function \( y = -3^x \), such as \( x = -1, 0, 1, 2 \). Calculate the corresponding \( y \) values: - For \( x = -1 \), \( y = -\frac{1}{3} \)- For \( x = 0 \), \( y = -1 \)- For \( x = 1 \), \( y = -3 \)- For \( x = 2 \), \( y = -9 \)
04
Plot the Points and Draw the Graph
Using the calculated points \((-1, -\frac{1}{3})\), \((0, -1)\), \((1, -3)\), and \((2, -9)\), plot these on a coordinate grid. Connect the points with a smooth curve, showing the exponential decay and reflection over the x-axis.
05
Analyze the Graph
Notice that as \( x \) increases, the values of \( y \) become more negative, confirming that the function is decreasing due to the negative sign. The graph will approach but never touch the x-axis, which acts as a horizontal asymptote.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphical Representation
Visualizing an exponential function can be quite insightful. For the function \( y = -3^x \), it is crucial to interpret its graphical attributes. When we graph this function, we see its unique behavior due to the negative sign preceding the \( 3^x \). This changes how the graph appears compared to standard exponential growth functions.
- The function follows a specifically mirrored pattern across the x-axis.
- This happens because each calculated \( y \) value is multiplied by -1.
Exponential Decay
The notion of exponential decay is central to understanding how the function \( y = -3^x \) behaves. Normally, exponential functions grow, showcasing exponential growth. However, the negative sign introduces decay rather than growth.Here's what happens:
- With exponential decay, the function values decrease rapidly.
- As \( x \) increases, \( y \) values drop fast but never hit zero.
Function Transformation
Transformations are crucial in shifting a function's graph. The function \( y = -3^x \) illustrates this well with its transformation from a basic exponential function. Let's explore these transformations:
- The negative sign in \( -3^x \) creates a vertical reflection.
- This transformation flips the graph over the x-axis.