Question 52654
a) (0,1), (4,1), (6,2), (2,0)
This is a function because for every x there is exactly one y.  Y's can have more than one x, but x's can have only one y.
The Domain corresponds with the x values is {0,4,6,2}, the range corresponds with the y values is {1,1,2,0}
b) y=6/(2x-1)
This is a function.  When dealing with equations it is often easiest to look at y.  If it's not raised to an even power it's a function.
For rational (fractions with variables in the denominator) functions the domain can be found by finding out what makes the denominator =0 (thus be undefined)
2x-1=0
2x-1+1=0+1
2x=1
2x/2=1/2
x cannot = 1/2  
Set builder notation:{x|x cannot=1/2}
Interval notation: (- infinity, 1/2)U(1/2,+infinity)
For the Range: y cannot eqaul 0.
Set builder notation:{y|y cannot=0}
Interval:(-infinity,0)U(0,+infinity)
I don't know what math you're taking, so I don't want to tell you too much about how I know the range and freak you out.  Resubmit that portion with the level of math you're in and I'll tell you how to find out that y cannot = 0.  If you're in algebra, you can probably just plug it into your graphing calculator and look at what y can't be.  If your in precal or calculus, take the limit as x approaches infinity.