1. ## Function Notation

$\displaystyle f \colon R \rightarrow R, f(x)=x^2$

What do the two Rs denote?

2. Originally Posted by DivideBy0
$\displaystyle f \colon R \rightarrow R, f(x)=x^2$

What do the two Rs denote?
They denote the set of all real numbers. So in this case the function is to be considered as taking any real number to another real number. That is the domain of $\displaystyle f$ is $\displaystyle \bold{R}$ and the range is a subset of $\displaystyle \bold{R}$

RonL