A community for students.
Here's the question you clicked on:
 0 viewing
Loujoelou
 2 years ago
Let f(x) = x^2 – 81. Find f–1(x).
Can someone doublecheck what I have?
Loujoelou
 2 years ago
Let f(x) = x^2 – 81. Find f–1(x). Can someone doublecheck what I have?

This Question is Closed

Loujoelou
 2 years ago
Best ResponseYou've already chosen the best response.0Okay so I know first to substitute f(x) with y and then to reverse the x & y variables which would give me x=y^281. Then I use a root on both sides and get \[\pm x=y9\] and finally I add 9 on both sides to get \[\pm 9 \sqrt{x} = y\]

Loujoelou
 2 years ago
Best ResponseYou've already chosen the best response.0well we have y^281, idk factoring it would be (y+9)(y9) but am I supposed to do that?

hartnn
 2 years ago
Best ResponseYou've already chosen the best response.2no, what you did was \(\sqrt{y^281}=y9\) that is incorrect. whats to be done : let y= x^281 add 81 to both sides. then take square root of both sides...

Loujoelou
 2 years ago
Best ResponseYou've already chosen the best response.0oh okay :) so it'd be x+81= y^2 and once we square root both sides would the answer come out to \[\pm 9 \sqrt{x}=y\]

hba
 2 years ago
Best ResponseYou've already chosen the best response.0@hartnn Bache mai halka haat rakho :)

hartnn
 2 years ago
Best ResponseYou've already chosen the best response.2taking square root on both sides of \(x+81=y^2\) will give you \(\sqrt{x+81}=\sqrt{y^2}=y\) to get the inverse function as \(\sqrt{x+81}\) got this ? hba, i didn't get you.

Loujoelou
 2 years ago
Best ResponseYou've already chosen the best response.0okay I get it :) thx a ton! :)
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.