Question

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Answer 1

Hmmm, how about something like... the natural log \(\ln(x)\)

Answer 2

Wait I totally over thought this. Just let \(f(x) = -x\). It will map any real number to a negative real number.

Answer 3

@jmallis Make sense?

Answer 4

No not really, but I'll eventually figure it out I suppose.

Answer 5

It's like a game. I ask for a rule which gives me a negative number for any positive number, and vice versa.

Answer 6

But you can't give me a rule that gives me two negative numbers for a single positive number.