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Rearranging equations help, GCSEs were a decade ago

Hello,

I went back into education after a while away and I need help with rearranging equations. Here is the example I'm trying to rearrange:
R/r = sqrt(f+p)/(f-p)

Attachment not found

I need to rearrange for f.

So far this is what I've done:

I have tried to move forward in various ways and none of them work. I actually managed to get rid of f somehow which is clearly not ideal. Any help would be appreciated but I really need some detailed advice. I can't continue to spend hours rearranging things and getting nowhere.

Reply 1

Shaanv

Next multiply both sides by r^2. Expand the brackets, then collect f terms on one side of the equals sign.

Let me know if u have any more questions or need further help

Reply 2

econflower

Original post by whatever24

So far this is what I've done:

I could be missing something here but you've literally done it? now all you have to do is subtract p from both sides and you have f on it's own = the rest of the equation ???????

Reply 3

Notnek

Original post by econflower

I could be missing something here but you've literally done it? now all you have to do is subtract p from both sides and you have f on it's own = the rest of the equation ???????