Confusion with Inverse Functions AP Calc

In summary, for the first problem, the goal is to find a value of x that makes the function f(x)= .01x³ + .7x -2 equal to 3. To do this, we need to find the inverse function and plug in the required number. For the second problem, we need to find the derivative of the inverse function g(x) and evaluate it at x=2.
  • #1
Loppyfoot
194
0

Homework Statement


1) Given f(x)= .01x³ + .7x -2 . Approximate ƒ−1(3).

2)Given f(x) = (x³) / (x²+1) and g(x) = ƒ–1(x). Evaluate g'(2)



The Attempt at a Solution



1) Would this be correct? 3=.01x^3 + .7x -2
But then, how would I find x at 3?


2) I am confused about going about solving this problem. Any help would be appreciated@!

Thanks
 
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  • #3
OK, so for number one, I wouldn't just set the function equal to 3 and then solve?? And if I would do that how would I find x??
 
  • #4
For #1, you're looking for a number x0 such that f(x0) [itex]\approx[/itex] 3. Equivalently, x0 [itex]\approx[/itex] f-1(3)
 
  • #5
So then I have 3=.01x^3 + .7x -2. What step would I take to solve this problem next?
 
  • #6
How about adding 2 to both sides? This will give you .01x^2 + .7x = 5. At that point I would pick a value and put it in for x on the left side and see how close I got to 5. If the result is larger than 5, pick a smaller value and repeat the process so that you get closer and closer to 5 as the result.
 

FAQ: Confusion with Inverse Functions AP Calc

1. What is an inverse function in AP Calc?

An inverse function in AP Calc is a function that undoes the action of another function. It is like running a process in reverse. For example, if the original function is f(x) = x^2, the inverse function would be f^-1(x) = √x.

2. How do you find the inverse of a function?

To find the inverse of a function in AP Calc, you can use the following steps:
1. Replace f(x) with y.
2. Swap the positions of x and y.
3. Solve for y.
4. Replace y with f^-1(x).
5. Simplify the equation if necessary.

3. What is the notation for an inverse function in AP Calc?

The notation for an inverse function in AP Calc is f^-1(x), where f represents the original function. This notation is read as "f inverse of x."

4. What is the relationship between a function and its inverse?

The inverse of a function is like a mirror image of the original function. They are symmetric about the line y = x. This means that if you graph both the function and its inverse on the same graph, they will intersect at (x, x). The domain of the original function is the range of its inverse, and vice versa.

5. How do inverse functions relate to composite functions?

Inverse functions and composite functions are closely related. When you compose a function with its inverse, you get the original input back. In other words, f(f^-1(x)) = x and f^-1(f(x)) = x. This is because the composition of a function and its inverse essentially cancels out the effects of each function, resulting in the original input value.

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