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May 9th, 2018, 02:52 PM   #1
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Tricky transposition problem

Hi guys, I'm working on a circuit problem here.
I've changed these variables to make them more mathish... if such a word exists. I seem to have got myself in a terrible web here, that I can't get out of.

At the moment, I'm here:

1 / x-y = z + 1 / w

I need it to be in a form something like

X = w + yz

or x = w + (y+z)


In case you haven't guessed, this x is a total impedance and the w y z are an rlc circuit. But no matter, the math is the same.

I feel like there's a piece of math I'm missing, a mathematical tool as such...

What to do with that -y? is my problem, without disturbing the rest of the equation. I've tried all sorts of things but just banging my head against the wall at this point.

Last edited by skipjack; May 9th, 2018 at 07:31 PM.
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May 9th, 2018, 02:59 PM   #2
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Quote:
Originally Posted by Kevineamon View Post
1 / x-y = z + 1 / w
should left side be: 1 / (x-y) ?

should right side be (z+1) / w ?
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May 9th, 2018, 04:44 PM   #3
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May 9th, 2018, 05:11 PM   #4
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Please answer my question.
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May 9th, 2018, 05:35 PM   #5
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I did try to Denis. I'm not really sure what you mean by the question.

As far as I'm aware z + (1 / w)
is not equalled to (z+1) / w

So to my mind you're basically asking the question - should 4 be 7?

No... Unless you're about to open up some philosophical debate, then I suppose my answer must be - maybe...
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May 9th, 2018, 05:38 PM   #6
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Quote:
Originally Posted by Kevineamon View Post
I did try to Denis. I'm not really sure what you mean by the question.

As far as I'm aware z + (1 / w)
is not equalled to (z+1) / w

So to my mind you're basically asking the question - should 4 be 7?

No... Unless you're about to open up some philosophical debate, then I suppose my answer must be - maybe...
He's merely asking you to provide parenthesis so we know what those expressions actually are.

So we now have 1/ x - y = z + (1/w). What is the LHS? (1/x) - y or 1/(x - y)?

-Dan
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May 9th, 2018, 06:01 PM   #7
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Ahh ok sorry guys, I was off sick on `common sense` dispensing day

LHS = 1 / (x-y)

RHS = z + (1/w)

That pic up there ^ is what I'm actually trying to do.
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May 9th, 2018, 07:03 PM   #8
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Quote:
Originally Posted by Kevineamon View Post
LHS = 1 / (x-y)

RHS = z + (1/w)
1 / (x-y) = z + (1/w)

Solving for x:
x = (w + y + wyz) / (wz + 1)
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May 9th, 2018, 07:28 PM   #9
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You have 1/(x - y) = z + 1/w, so x = y + 1/(z + 1/w).

The right-hand side of that can be rearranged in various ways. Changing the left-hand side further should be unnecessary, as it's already what you want.

You mentioned trying "several bouts of rearranging", but you didn't post the full details. I suspect you did the rearranging incorrectly. Assuming that you've made some slips, how do we know that your original equation is correct?
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May 9th, 2018, 08:25 PM   #10
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Sigh I don't know at this stage... Really I don't, I asked a question a number of days ago on another forum. This was the question:-

How did he get from here to there?



Now you'd have thought that would have been a simple enough question, right?
Wrong... Since then I've been on about a 2 day mission, on various errands, trying to find out.

Apparently if I figure out the first equation in the first picture I posted, then I will receive enlightenment...

Now since my journey began, some days ago - I don't know if I've got it my equations wrong, though I don't think so, or the guy on the other forum, would have shouted at me already. I'm at that point in the pic, the middle bit

1/(Zt-jwl) = jwc + (1/R)

All I want to do is get that (-jwl) over to the RHS

Please help!!!
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