Inverse Functions

1 / 16

# Inverse Functions - PowerPoint PPT Presentation

Inverse Functions . End In Mind. Prove that and are inverses of each other Complete warm up individually and then compare to a neighbor. Vocabulary . Function: a relation in which each input x has exactly 1 output y

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Inverse Functions' - kaethe

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
End In Mind
• Prove that and are inverses of each other
• Complete warm up individually and then compare to a neighbor
Vocabulary
• Function: a relation in which each input x has exactly 1 output y
• Inverse of a Function: The inverse function is a function that undoes another function: If an input x in the function ƒ produces an output y, then putting y into the inverse function g produces the output x, and vice versa.
• One to One: A function is one to one if every output y, has exactly 1 input x.
• Horizontal Line Test - A function f is one to one if and only if each horizontal line intersects the graph at most once.
• Composition of Functions: is the process of combining two functions where one function is performed first and the result of which is substituted in place of each x in the other function. The composition of functions f and g is written as f o g. [f o g](x) = f[g(x)]
Inverse Functions
• An inverse function undoes what the function does

f(x)

range

domain

Can you mentally determine the inverse of the functions?

Solving for an inverse algebraically

Finding the inverse of a function

Problem:

• Replace f(x) with a y
• Switch the x and y
• Solve for y
• Replace y with f-1(x)
Finding compositions
• To find a composition of 2 functions, substitute one function for the other function:

Example: f(x)= 3x-8 and g(x) = x2+1

• To find f(g(x))=f○g(x)

substitute the g(x) function

for the f(x) function

f(g(x))=f○g(x) = 3(x2+1)-8

=3x2+3-8

=3x2-5

• To find g(f(x))=g○f(x), substitute the f(x) function for the g(x) function:
• g(f(x))=g○f(x) = (3x-8)2+1
• =(3x-8)(3x-8)+1
• =9x2-48x+64+1
• =9x2-48x+65
Verifying inverses an application of compositions

To verify that two functions are inverses then,

Using our earlier problem,

Verify that and are inverses of each other.

End In Mind
• Prove that and are inverses of each other
End In Mind
• Determine the inverse values of the function from the table:
Inverses Graphically
• Graphing inverse functions

The graph of the inverse of f is the reflection of f over the line y=x

Horizontal Line Test
• Existence of an Inverse function

a function f has an inverse function if and only if the function is one to one.

• One to One

a function f is one to one if for every y there is exactly one x value

• Horizontal line test
Determine whether the function is invertible. If it is, find it’s inverse

a. {(4,3),(2,-1),(5,6)}

b. {(9,0),(8,1)(,4,0)}

c.

d.

Yes. {(3,4),(-1,2),(6,5)}

Not invertible. Since 2 y values are the same.

Not invertible since all y values are the same.

End In Mind
• Determine the inverse values of the function from the table:
Use y=x2+5

End in Mind: limit the domain so that the inverse is a function

Is the relation a function?

Graph the function.

Does the inverse exist?

How could you limit the domain so that the function will have an inverse?

Graph the inverse with the restricted domain. How can you verify that the graph of the inverse exits?

Ticket Out

http://www.regentsprep.org/Regents/math/algtrig/ATP8/indexATP8.htm

GO to the above website for further explanations. You must do the practice problems. Each problem will tell you if you are right or wrong. If you need help, click the explanation button