# Origin of "subject of an equation"

1. Oct 2, 2015

### Staff: Mentor

I started to wonder (not for the first time) when (and where?) the term "subject" became common, for the variable on the left side of an equation or formula? I'm pretty sure nobody talked about "changing the subject of an equation" when I was in school in the 1960s, or in college in the 1970s, in the US. I don't remember students in my college physics classes using it from the 1980s onwards. I've always said something like "solving the equation for <variable name>." However, I've been pretty much out of touch with trends in high school algebra-instruction. Or maybe this is a British versus US thing?

Last edited: Oct 2, 2015
2. Oct 2, 2015

### mrnike992

I'll second that, I've never heard of it, and the other user in that thread hasn't either.. I don't think it's a thing at all.

EDIT: All of the instructional videos on youtube about "Changing the subject" of an equation are done in a British accent, so that's my guess.

3. Oct 3, 2015

### Ben Niehoff

I thought this was an Indian thing. It might be from an older British usage, but the Indian English dialect has developed some of its own conventions.

Another one is saying "three by five" to mean 3/5, where we'd say "three over five", or maybe "three divided by five". Some people also say "three upon five", but I'm not sure what part of the world that comes from.

4. Oct 3, 2015

### Ben Niehoff

After Googling it, "changing the subject" of an equation appears to be a British-ism. It is not one I've actually heard in person except from Indians, though.

5. Oct 3, 2015

### Daz

If it is a British-ism then it must be a fairly recent thing. I'm a Brit and I don't recall ever hearing "the subject of an equation" during my time at school or university.

6. Oct 3, 2015

7. Oct 3, 2015

### FeDeX_LaTeX

I heard this phrase all the time back at school. (I'm from London.)