1. **Problem statement:** Given the function $f(x) = \frac{1}{x+5}$, find the domain and range of its inverse $f^{-1}$, and determine if it is possible to do this without finding the expression for $f^{-1}$.
2. **Recall the domain and range of $f(x)$:**
- The domain of $f$ is all real numbers except where the denominator is zero, so $x \neq -5$. Thus, domain of $f$ is $(-5, \infty)$ or $(-\infty, -5) \cup (-5, \infty)$.
- The range of $f$ is all real numbers except zero, since $\frac{1}{x+5}$ never equals zero. So range of $f$ is $\mathbb{R} \setminus \{0\}$.
3. **Domain and range of the inverse function:**
- The domain of $f^{-1}$ is the range of $f$, so domain of $f^{-1}$ is $\mathbb{R} \setminus \{0\}$.
- The range of $f^{-1}$ is the domain of $f$, so range of $f^{-1}$ is $\mathbb{R} \setminus \{-5\}$.
4. **Finding $f^{-1}(x)$ explicitly:**
Start with $y = \frac{1}{x+5}$. Swap $x$ and $y$ to find inverse:
$$x = \frac{1}{y+5}$$
Multiply both sides by $y+5$:
$$x(y+5) = 1$$
$$xy + 5x = 1$$
Solve for $y$:
$$xy = 1 - 5x$$
$$y = \frac{1 - 5x}{x}$$
Simplify by splitting the fraction:
$$y = \frac{1}{x} - 5$$
So,
$$f^{-1}(x) = \frac{1}{x} - 5$$
5. **Domain and range from the inverse expression:**
- Domain of $f^{-1}$ is all real numbers except $x \neq 0$ (since division by zero is undefined).
- Range of $f^{-1}$ is all real numbers except $y \neq -5$ (since $\frac{1}{x}$ never equals zero).
6. **Is it possible to find domain and range of $f^{-1}$ without finding $f^{-1}$?**
Yes, by using the fact that the domain of $f^{-1}$ is the range of $f$, and the range of $f^{-1}$ is the domain of $f$. However, to understand asymptotes and behavior fully, finding the explicit expression helps.
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7. **Problem statement:** Given a one-to-one function $g$ with a vertical asymptote at $x = -5$ and the table of values:
\begin{tabular}{c|c}
x & g(x) \\
\hline
-5 & \text{undefined} \\
-2 & -14 \\
0 & -11 \\
3 & -1 \\
6 & 0
\end{tabular}
(a) Find the $y$-intercept of $g^{-1}$.
(b) Write the equation for the horizontal asymptote of $g^{-1}$.
8. **Solution for (a):**
The $y$-intercept of $g^{-1}$ is the value of $g^{-1}(0)$. Since $g^{-1}$ swaps $x$ and $y$, the $y$-intercept of $g^{-1}$ corresponds to the $x$ value where $g(x) = 0$. From the table, $g(6) = 0$, so
$$g^{-1}(0) = 6$$
Thus, the $y$-intercept of $g^{-1}$ is 6.
9. **Solution for (b):**
The vertical asymptote of $g$ at $x = -5$ becomes a horizontal asymptote of $g^{-1}$ at $y = -5$.
Therefore, the equation of the horizontal asymptote of $g^{-1}$ is
$$y = -5$$
Inverse Domain Range 77E824
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