synonyms for "solve for x" or "isolate x"

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skullturf
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synonyms for "solve for x" or "isolate x"

Postby skullturf » Tue Aug 21, 2012 6:27 pm UTC

This is a question about mathematical terminology learned in school in different parts of the world.

I'm from North America (born and raised in Canada, now living and working in the United States).

For me, if we rearrange an equation to put one variable by itself on one side, such as

Ax + B = C

becoming

x = (C-B)/A

I would call that "solving for x" or "isolating x".

I seem to recall encountering other words for this process, perhaps even on these very boards. But I'm drawing a blank at the moment. Can anybody help me remember other words for this? (For instance, do people in the UK sometimes call this by a different name? Or India, South Africa, etc., etc.?)

rolo91
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Re: synonyms for "solve for x" or "isolate x"

Postby rolo91 » Tue Aug 21, 2012 6:48 pm UTC

In spanish we use the ones you said, and sometimes "encontrar x" (find x). Is that the synonym you were looking for?

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Re: synonyms for "solve for x" or "isolate x"

Postby dudiobugtron » Tue Aug 21, 2012 7:16 pm UTC

We often call this "making x the subject". I'm interested to hear some other names for it too though!
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Re: synonyms for "solve for x" or "isolate x"

Postby skullturf » Tue Aug 21, 2012 7:16 pm UTC

Aha! I just remembered it!

It was "make x the subject".

I don't remember hearing that when I was a student. But nevertheless, maybe it is used in North America, but only by some people.

Or perhaps it's not North American at all.

Anyone happen to know?

(Heh. Ninja'd!)

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Re: synonyms for "solve for x" or "isolate x"

Postby TheGrammarBolshevik » Tue Aug 21, 2012 9:04 pm UTC

How about "determine X"? For example, someone asked for help with the following problem on reddit recently: "Assume f: Z to A given by f(x)=2x-5 is onto. Determine the set A."
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Re: synonyms for "solve for x" or "isolate x"

Postby eSOANEM » Tue Aug 21, 2012 10:40 pm UTC

(UK here)

I usually here "find x" or "solve for x" (or just "solve" it's obvious what variable to solve for) with "make x the subject" being used only in slightly more formal contexts.
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Kirby
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Re: synonyms for "solve for x" or "isolate x"

Postby Kirby » Wed Aug 22, 2012 12:42 am UTC

dudiobugtron wrote:We often call this "making x the subject". I'm interested to hear some other names for it too though!


I'm in the U.S. (Texas) and have not heard that one before. Usually it's just "solve for x."

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Re: synonyms for "solve for x" or "isolate x"

Postby dudiobugtron » Wed Aug 22, 2012 2:21 am UTC

They do mean slightly different things for me in New Zealand. "Make x the subject" means to rearrange the equation so that x is isolated; nominally you don't need to find an 'answer'. 'Making x the subject' is really the technique you need to use in order to solve for x.

egs:

You wouldn't ask someone to "make x the subject" of, say, 2x+4=8. You would ask them to 'solve for x' or 'calculate x', since you can get a numerical answer.

You'd normally use "make x the subject" for an equation like y=2x+4, or y=mx+c. (I guess you could also write "solve for x, in terms of m, y and c"...)
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PM 2Ring
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Re: synonyms for "solve for x" or "isolate x"

Postby PM 2Ring » Thu Aug 23, 2012 10:18 am UTC

dudiobugtron wrote:You'd normally use "make x the subject" for an equation like y=2x+4, or y=mx+c. (I guess you could also write "solve for x, in terms of m, y and c"...)


Another option there is "express x in terms of m, y and c".

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Re: synonyms for "solve for x" or "isolate x"

Postby Carteeg_Struve » Fri Sep 14, 2012 11:46 am UTC

Here in New England I usually hear "Solve for x" or "Find x". I have never heard "isolate x", "determine x", or "make x the subject" before.


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