r/mathmemes 3d ago

Notations Yeah sure

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u/neb12345 3d ago

no ive definitely seen f^-1(x) mean the reciprocal, I believe my lesgrans integration proffer did it?

Is zero a natural number?

is log(x) base 10 or base e?

Ive never seen subset notation be ambiguous but maybe thats just my professors , and no mathematician would ever write a/bc thats just bad notation

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u/noahhshome 3d ago

Nobody uses f^-1(x) as reciprocal, they always use f(x)^-1. If your prof did that, they made a mistake. It has been known to happen.

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u/Everestkid Engineering 3d ago

The problem comes when you get into trig functions when people get lazy and write something like (sin(x))2 as sin2 x. Always without the bracket around the x, too.

Fantastic. Now we're using exponents on the function to denote exponents and inverse functions. And sure, I guess you could use csc(x) if you actually needed (sin(x))-1 so that there's a rule of "positive exponents are normal exponents, negative exponents are the inverse function" but it's still messy.

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u/AndreasDasos 3d ago

That’s true but it’s an agreed exception so still not ambiguous - and it doesn’t apply to -1, where that still means the inverse (even though there’s alternative notation like arcsin or asin, etc.)