One-to-One function? In text it states that a one to one function is “A function f is one to one if for any two range values f(u) and f(v), f(u)=f(v) implies that u=v. What exactly does this mean? I thought if there are two equal y values it is NOT a one to one function?

One to one means:  For every output there is exactly one input.
Or in other words,  If two times you got the same out put, then you must have had the same input.
Or in other words.  If you got $f(u) = f(v)$ that means $u = v$.
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Or... one to one means.  If $u \ne v$ then $f(u) \ne f(v)$.... so if you ever DO find yourself with $f(u) = f(v)$ the only way that can possibly happen is if $u = v$.
Basically the two statements:
i)  If $u \ne v \implies f(u) \ne f(v)$ and 
ii) If $f(u) = f(v) \implies u = v$
are both equivalent.  ii) is just the contrapositive of i).
"Cheap food is not good" is the contrapositive of "Good food is not cheap".  THey both mean exactly the same thing.
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To do an example.  
Suppose $f(x) = x^3$ we'll take it for granted that we know $f$ is one-to-one.
Suppose $f(u) = f(v) = 8$.  Then what is $u$ and what is $v$? 
Well $v^3 = 8$ so $v =\sqrt[3]8 = 2$.  And $u^3 = 8$ so $u = \sqrt[3]8 = 2$ and .... what do you know!  $u = v$!  What were the odds!
