# does anyone know what this means?

• Jul 7th 2008, 01:14 PM
tara
does anyone know what this means?
Given to me by my math teacher. We were told it was some kind of proof but I dont really understand what it means...

pf (f^1 (x)) = x

any ideas?

Thanks guys
• Jul 7th 2008, 02:02 PM
Matt Westwood
What's the context? "pf" could mean "probability function", apart from that I haven't a clue. What level of mathematics - grade school, high school, university, postgrad? What field: probability/statistics, analysis, calculus, graph theory, topos theory, what?
• Jul 7th 2008, 02:18 PM
tara
College pre-calculus and we are working on function, maxima, stretching, that kind of thing. thank you for answering...
• Jul 7th 2008, 03:17 PM
Jhevon
Quote:

Originally Posted by tara
Given to me by my math teacher. We were told it was some kind of proof but I dont really understand what it means...

pf (f^1 (x)) = x

any ideas?

Thanks guys

ok, so i do not know what "pf" is supposed to mean. perhaps you copied it wrong. this may have to do with inverse functions, that's the closest thing i see to this.

note that if \$\displaystyle f(x)\$ and \$\displaystyle f^{-1}(x)\$ (the usual notation for inverse functions) are inverses of each other, then:

\$\displaystyle f(f^{-1}(x)) = x\$ and \$\displaystyle f^{-1}(f(x)) = x\$ ..........that is, the composition of a function and it's inverse remains fixed. whatever the input is, that's what the output will be