Chapter 8: Problem 26
Graph each function. $$ y=(0.25)^{x} $$
Short Answer
Expert verified
The graph of the function \(y = (0.25)^x\) starts at the y-intercept (0,1) and decreases, approaching but never reaching the x-axis (the line y = 0).
Step by step solution
01
Identify the y-intercept
The y-intercept of a function is the point where the line cuts the y-axis. For any exponential function in the form \(y = a^{x}\), when x=0, y equals 1 because any non-zero number raised to the power of 0 equals 1. So, for our function \(y=(0.25)^{x}\), when x=0, \(y=(0.25)^0=1\). Hence, the y-intercept is at (0,1).
02
Identify the horizontal asymptote
Horizontal asymptotes are lines that the graph approaches but never touches. For an exponential function in the form \(y = a^{x}\), as x tends to positive infinity, y tends to 0. Hence, the line y=0 is a horizontal asymptote.
03
Plot the key points
The y-intercept is (0,1) and the horizontal asymptote is y=0. The graph increases from left to right and is getting closer and closer to the x-axis but never touches it. The graph passes through the y-intercept and tends to the x-axis as x tends to infinity.
04
Draw the graph
Using the y-intercept and horizontal asymptote, sketch the graph. Remember that the graph will never drop below the x-axis, so the area under the x-axis (where y < 0) should be left blank.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing
Graphing exponential functions is a fun and insightful way to understand their behavior in a visual format. Let's break down the process:- **First**, identify the equation of the exponential function you are dealing with, like \( y = (0.25)^x \).- **Next**, compute important features like the **y-intercept** and the **horizontal asymptote**.When graphing this function, plot its y-intercept first, which is the point where the graph crosses the y-axis. Since our function is of the form \( y = a^x \), the graph will cross at the y-intercept of (0, 1) by default when x equals zero because any non-zero number to the power of zero is one.As you draw the graph, notice how it behaves. It starts from the y-axis and approaches the x-axis as it extends to the right. These curves are smooth and reflective of the exponential decay in this example (since 0 < 0.25 < 1). Recall, the graph never actually touches the x-axis but gets very close, which introduces the concept of asymptotes that we'll explore next. Moreover, make sure your plot showcases:
- A continuous curve without breaks.
- A smooth transition passing through the y-intercept.
- Approach towards the x-axis as x increases, indicating decay.
Horizontal Asymptote
A horizontal asymptote in exponential functions tells us about the behavior of the graph as x approaches positive or negative infinity. For the function \( y = (0.25)^x \), this is a line that the function comes infinitesimally close to but never actually reaches or crosses.In our case, as x increases, \( y = (0.25)^x \) tends towards zero but will not become negative or reach zero. This creates a horizontal asymptote at \( y = 0 \).Here are some key points about horizontal asymptotes:
- They do not affect the y-intercept or the initial behavior of the graph, rather they define the behavior at extreme x-values.
- The asymptote with \( y = (0.25)^x \) is horizontal because the exponential base is positive and smaller than 1, indicating decay as x grows.
Y-Intercept
The y-intercept is a key point on the graph of a function, providing an easy starting location for plotting. For exponential functions like our example \( y = (0.25)^x \), finding the y-intercept is straightforward and involves evaluating the function at x = 0.When substituting x = 0 into the equation, it simplifies to \( y = (0.25)^0 = 1 \). Thus, the graph crosses the y-axis at the point (0, 1).Here are some essential aspects regarding y-intercepts:
- It is always calculated by setting x to zero in the exponential function.
- The y-intercept for any exponential function \( y = a^x \) with a constant base "a" will always be at y = 1, assuming no vertical shifts.
- This starting point is foundational for plotting the rest of the function as it helps dictate the initial slope and direction of the curve.