Solving for X in a Fractional Equation

[rede96]

Hi,

I should know this but havn't done any transposition of formula for a long, long while :)

If I know y and z, how can I solve for x in the following formula:

X ÷ (X + Y) = Z

Thanks.

 

[tiny-tim]

hi rede96!

multiply both sides by (x+y)

 

[rede96]

hi rede96!

multiply both sides by (x+y)

Thanks tiny-tim.

So I would get X = Z (X + Y) or X = ZX + ZY

But as I am feeling very mathematically challenged today, can you demonstrate solving for x when y = 28 and z = 0.3 please.

 

[HallsofIvy]

Step 2: Subtract ZX from both sides of the equation.

 

[rede96]

Step 2: Subtract ZX from both sides of the equation.

Ok, so now I have X - ZX = ZY.

I assume that there are a few more steps but I'll be dammed if I can remember.

From memory I know I need to remove the Z from the ZX on left hand side of the equation, but can't figure out how.

Rather than go through this one step at a time, I would very much appreciate it if someone could give me the answer then I can work backwards.

Just by playing with the numbers I figured out that X = (Y / (1-Z)) - Y but have not figured out yet how to get there!

 

[Mark44]

Step 3: Factor x from the two terms on the left side.
I'm hopeful you can figure out step 4 (the last step) on your own.

I assume that there are a few more steps but I'll be dammed if I can remember.

Does that mean you are a river?

 

[rede96]

Step 3: Factor x from the two terms on the left side.
I'm hopeful you can figure out step 4 (the last step) on your own.

Does that mean you are a river?

Well if you mean do I feel that I am about to burst then yes! So either dammed or damned would do!

Thanks for the help, still not figured it but am really busy at the mo, so will have a look later.

Red.

 

[KingNothing]

When you are done, you can use http://www.wolframalpha.com" to check your answer. You can type in things like "x/(x+y)=z, solve for x". It will also show you the steps in doing so if you choose "show steps".

 

[rede96]

When you are done, you can use http://www.wolframalpha.com" to check your answer. You can type in things like "x/(x+y)=z, solve for x". It will also show you the steps in doing so if you choose "show steps".

Cool, thanks. Just wish I could remember all this stuff!

 

[jtbell]

Ok, so now I have X - ZX = ZY.

Hint: X = 1X (one times X), so this becomes

1X - ZX = ZY

What can you do with the left-hand side now, so you end up with a single X?