# Math Help - Isolating x?

1. ## Isolating x?

Is it possible to isolate x in the following: f(x) = -4 +2x / 5 + x? If so, how?

2. ## Re: Isolating x?

Originally Posted by Dmiller93
Is it possible to isolate x in the following: f(x) = -4 +2x / 5 + x? If so, how?
Not sure of the question??
If $y=\frac{-4+2x}{5+x}$ then it is possible to write $x$ as a function of $y$.

Is that the same as your question?

3. ## Re: Isolating x?

Yes, it's the same.

4. ## Re: Isolating x?

Originally Posted by Dmiller93
Yes, it's the same.
From reply #2, just solve that equation for x in terms of y.

5. ## Re: Isolating x?

Sorry, could you clarify? I'm not quite sure how to go about doing that.

6. ## Re: Isolating x?

Rewrite:
$y=\frac{-4+2x}{5+x}$
$\Leftrightarrow y(5+x)=-4+2x$
$\Leftrightarrow 5y+yx=-4+2x$
$\Leftrightarrow 2x-yx=5y+4$
$\Leftrightarrow x(2-y)=5y+4$
$\Leftrightarrow x=...$