Hey guys,

I am trying to prove the following function is one-to-one and onto.

D=Q\{4}, R=\{2} and F-->R is f(x) = (2x + 3)/(x-4) for all x in D.

Here is my work so far:

One-to-One:

Let f(x1) = f(x2)

(2X1 + 3)/(X1 + 4) = (2X2 + 3)/(X2 + 4)

Ok, so I know I have to end up with x1=x2, but from here, I get stuck. (seems more like an algebra problem from here, but can somebody show me how to end up with x1=x2 from here)

Onto:

Let y be an element of Q.

Suppose f is onto.

Then there exist some x in D s.t. f(x)=y.

f(x) = (2x+3)/(x-4) = y

Now I have to solve for x, and once again, I don't know how to solve for x. Seems I missed this part in Algebra class. Please show me how to solve for x.

Also, am I on the right track to proving these