for a function f(x).
A) if f(7)=22 then f^-1(22)=
B) f^-1(f(c))=

**PLEASE HELP**

Question

for a function f(x).
A) if f(7)=22 then f^-1(22)=
B) f^-1(f(c))=

**PLEASE HELP**

anonymous · Answer

can u help me??

slaaibak · Answer

A) 7
B) c

anonymous · Answer

how do u do it?

zarkon · Answer

you should probably specify in the beginning of your problem the f has an inverse.

anonymous · Answer

the worksheet that i have only said that problem

anonymous · Answer

thats why i am so lost on this worksheet

anonymous · Answer

$$f(x)=y$$
$$f^{-1}(y)=x$$

anonymous · Answer

is that how you start it?

anonymous · Answer

you should use this rule

anonymous · Answer

ok thank you

myininaya · Answer

if this is the problem
then A and B may have the answers don't exist since we don't know if f is 1 to 1

myininaya · Answer

you should say not enough information

myininaya · Answer

as the answer

slaaibak · Answer

even if the function isn't one-to-one, won't those be at least one of the answers?

zarkon · Answer

it would be an element of the preimage.

myininaya · Answer

f^{-1}(something) should give a unique output for each input something

we may have f(-7)=22 also (or f(24)=22 or whatever)
so f^{-1}(22)=-7 there could be multiple answers for this 
and there should not be multiplie answers for this

myininaya · Answer

we need f to be 1 to 1

zarkon · Answer

if $$f:D\to R$$

then for any $$x\in R$$

$$f^{-1}(x)=\{a\in D|f(a)=x\}$$

myininaya · Answer

so you are saying f inverse does not have to be 1 to 1 ?

zarkon · Answer

if you want a true inverse function...then yes.

but you can still look at the preimage no matter what

myininaya · Answer

but i don't wanna lol

myininaya · Answer

so therefore the answer to me is not enough information

zarkon · Answer

ok  :)

I'm sure for these problems we are supposed to assume that the function has an inverse

myininaya · Answer

maybe

myininaya · Answer

this might be a trick question though

zarkon · Answer

could be

slaaibak · Answer

Yeah, it's only to test basic inverse knowledge, my opinion

myininaya · Answer

maybe 
the student should right
assuming f is 1 to 1 then the answers are what slaaibak gave
without that assumption there is not enough information 
or assuming f is not 1 to 1 there is not an inverse

myininaya · Answer

well it is inverse knowledge to know when an inverse exist

myininaya · Answer

god my english sucks like zarkon's
write not right

slaaibak · Answer

haha, yeah, that's correct.

myininaya · Answer

good game