What are the domain and range for the inverse function $f^{-1}$ of $f$?

In summary, we found the inverse function $f^{-1}$ of $f$ by exchanging $x$ and $y$ and solving for $y$, resulting in $f^{-1}(x)=\sin^{-1}\left(\frac{x-2}{5}\right)$. We also determined that the range of $f$ is $[-\frac{\pi}{2},\frac{\pi}{2}]$, which is also the domain and range of $f^{-1}$. This was found by using the fact that the domain of $f(x)$ is the range of $f^{-1}(x)$, and the range of $f(x)$ is the domain of $f^{-1}(x)$. Additionally,
  • #1
karush
Gold Member
MHB
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Find the inverse function $f^{-1}$ of $f$.
Find the range of $f$ and the domain and range of $f^{-1}$
$$f(x)=5 \sin x +2; \quad -\frac{\pi}{2}\le x \le \frac{\pi}{2}$$
exchange x for y and solve for y
\begin{align*}\displaystyle
x&=5\sin y + 2 \\
\frac{x-2}{5}&=\sin y
\end{align*}
multiply $\sin^{-1}$ to both sides
$$\sin^{-1}\left( \frac{x-2}{5}\right)
=\sin^{-1}(\sin y)=f^{-1}(x)$$

ok how do get the range of $f$ and domain and range of $f^{-1}$
 
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  • #2
Recall that the domain of $f(x)$ is the range of $f^{-1}(x)$, and the range of $f(x)$ is the domain of $f^{-1}(x)$.

So, you are given that the domain of $f(x)$ is $[-\frac{\pi}{2},\frac{\pi}{2}]$.
Therefore, the range of $f^{-1}(x)$ is $[-\frac{\pi}{2},\frac{\pi}{2}]$

Use this idea to determine the range of $f(x)$ and domain of $f^{-1}(x)$. (they should be the same thing)

We know that,
$-1 \leq sinx \leq 1$
If that is the range for $sinx$ then how will that change for $5sinx+2$?
 
  • #3
A technical point: please don't say "multiply [tex]sin^{-1}[/tex] to both sides". That sounds like you think "[tex]sin^{-1}[/tex]" is a number. What you mean is "apply the function [tex]sin^{-1}[/tex] to both sides".
 

1. What is the meaning of "8.8.53" in the context of domain and range?

"8.8.53" refers to a specific point or value on a graph. In the context of domain and range, it represents the coordinates (x,y) of a point where the x-value is 8.8 and the y-value is 53.

2. How is "8.8.53" related to the concept of domain?

In the concept of domain, "8.8.53" represents the input or independent variable of a function. It is the set of all possible values for the x-coordinate of a point on a graph.

3. What does "8.8.53" represent in terms of range?

In terms of range, "8.8.53" represents the output or dependent variable of a function. It is the set of all possible values for the y-coordinate of a point on a graph.

4. Can "8.8.53" be a part of both the domain and range?

Yes, "8.8.53" can be a part of both the domain and range. This means that there is a point on the graph with coordinates (8.8, 53), which is both an input and output of the function.

5. How can I determine the domain and range from a graph with "8.8.53" as a point?

To determine the domain and range from a graph with "8.8.53" as a point, you can look at the x- and y-axis to see what values they cover. The x-axis represents the domain and the y-axis represents the range. In this case, the domain would be all possible values for x between 0 and 10, and the range would be all possible values for y between 0 and 60.

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