Question

if f(x) = x + 10 find (f of f^-1)(5)?
is it all real numbers, 0, 5, or x?

Answer 1

f^-1 means "f inverse" or the function that "undoes" the function f.
example if f meant x^2 then f^-1(x) would be sqrt(x)
so what happens if you do square(sqrt(4))? Let's see: sqrt(4)= 2. square(2)= 4
Does that give you an idea of what the answer is?

Answer 2

so i need to find the sqr root of 10?

Answer 3

I don't mean to confuse you. That was an example of a function and its inverse. The question is asking about a different function and its inverse. But the idea is that a function and its inverse together end up giving back the number they start with.

Answer 4

haha im still lost? so its x?

Answer 5

well, another way to answer this question is to find the inverse of f(x)=x+10
it is
f^-1(x)= x-10

now form: f of f^-1 by replacing x in f(x)= x+10 with f^-1

Answer 6

you get f of f^-1 = x
and (f of f^-1)(5) = 5

Answer 7

you dont understand.. im not smart at all math is my worst subject!

Answer 8

behind all the mumbo jumbo are ideas that often are not too hard to understand.
so think like this
f(x) is a "thing" that you give an "x" to and it returns a "y" (x and y are numbers)
f^-1(y) does the opposite. you give it y, and it returns x.
so f(5) returns some number (call it y)
f^-1(y) will return the 5

Answer 9

Here is how it works with this problem
f^-1(x)= x-10 and f^-1(5)= 5-10= -5
now put the -5 in f(x)=x+10
f(-5)= -5+10= 5

that means (f of f^-1)(5)= 5