Chapter 5: Problem 15
Graph the function and specify the domain, range, intercept(s), and asymptote. $$y=e^{x}+1$$
Short Answer
Expert verified
Domain: (-∞, ∞); Range: (1, ∞); y-intercept: (0, 2); Asymptote: y=1.
Step by step solution
01
Understand the Function
The given function is \(y = e^x + 1\). This function involves the natural exponential function \(e^x\), which is shifted upward by 1 unit. The base of the natural exponential function \(e\) is approximately 2.718.
02
Determine the Domain
The domain of any exponential function is all real numbers because \(e^x\) is defined for every real number \(x\). Thus, the domain for the function \(y = e^x + 1\) is \((-\infty, \infty)\).
03
Determine the Range
The range of \(e^x\) is \((0, \infty)\) since the function never reaches negative values. With the transformation \(e^x + 1\), the entire graph is shifted up by 1 unit, changing the range to \((1, \infty)\).
04
Identify the Intercept(s)
Intercepts are points where the graph crosses the axes. For the y-intercept, set \(x = 0\): \(y = e^0 + 1 = 1 + 1 = 2\), so the y-intercept is \((0, 2)\). The function has no x-intercept as it never crosses the x-axis (since \(y\) never reaches 0).
05
Determine the Asymptote
An asymptote is a line that the graph approaches but never touches. For \(y = e^x + 1\), as \(x\) approaches negative infinity, \(y\) approaches 1, indicating a horizontal asymptote at \(y = 1\).
06
Graph the Function
Plot the graph starting by drawing the horizontal asymptote \(y = 1\). Plot the y-intercept at \((0, 2)\). For positive \(x\)-values, the graph increases exponentially, and for negative \(x\)-values, it approaches the asymptote from above.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Domain of a Function
The domain of a function tells us the possible values of the independent variable, typically denoted as \(x\). For the function \(y = e^x + 1\), we need to determine for which values of \(x\) the function is defined.
Exponential functions, like \(e^x\), are defined for all real numbers. This is because you can raise the constant \(e\) (approximately 2.718) to the power of any real number and still get a valid result. Therefore, nothing restricts the input \(x\) for this function.
Exponential functions, like \(e^x\), are defined for all real numbers. This is because you can raise the constant \(e\) (approximately 2.718) to the power of any real number and still get a valid result. Therefore, nothing restricts the input \(x\) for this function.
- In other words, \(x\) can be any real number.
- \((-fty, fty)\).
Range of a Function
The range of a function is all the possible values that the function can output. For exponential functions such as \(e^x\), the values start getting interesting. Let's explore this!
- The basic form \(e^x\) has a range of \((0, fty)\). This means it never outputs negative values and never actually equals zero.
- For \(y = e^x + 1\), each output of \(y = e^x\) is simply increased by 1. This shifts the entire range upward by 1 unit.
- \((1, fty)\).
Intercepts
Intercepts are points where the graph of a function crosses the axes.
- Y-Intercept: To find where the graph crosses the y-axis, we set \(x = 0\). For \(y = e^x + 1\), we get \(y = e^0 + 1\) which simplifies to \(y = 2\). So, the y-intercept is at the point \((0, 2)\).
- X-Intercept: This point occurs where the graph crosses the x-axis. It's found by setting \(y = 0\). However, since the expression \(e^x + 1\) is always greater than 1, it never reaches 0. Hence, there are no x-intercepts.
Asymptotes
Asymptotes are invisible lines that the function approaches but never touches. They guide us to understand the behavior of a function at the extremes.
For \(y = e^x + 1\):
For \(y = e^x + 1\):
- Vertical Asymptotes: Exponential functions don't have vertical asymptotes. They occur in fractions where there's a number divided by \(x\), which doesn't apply here.
- Horizontal Asymptotes: The line \(y = 1\) is a horizontal asymptote. As \(x\) approaches negative infinity, the value of \(y = e^x\) approaches 0, making \(y = 1\) the closest line the graph approaches but never quite reaches.