How do you pronounce x' and x''?

Question

I am giving a presentation tonight, and the mathematical terms x' and x'' feature heavily in it. I pronounce them as "x-dash" and "x-dash-dash", but this gets a bit tiresome by the end of the presentation.

A - Am I correct in pronouncing them this way? B - Is there an alternative way of saying x' and x'' that is less of a mouthful?

They are x prime and x double prime. A dash is a hyphen, so x dash is definitely not correct. — Brian M. Scott, Feb 19 '15 at 23:01
If you want to be old-fashioned, you can say "$x$ prime", "$x$ second", "$x$ third", etc. — Zhen Lin, Feb 19 '15 at 23:34
I use "x prime" and "x prime prime" myself. (I don't like "double prime" since it feels like an abbreviation that is actually longer than what it abbreviates) — Milo Brandt, Feb 20 '15 at 00:50
possible duplicate of How do you pronounce the symbol $'$ in $f'$? — apnorton, Mar 09 '15 at 22:20

score 7 · Answer 1 · answered Feb 20 '15 at 00:34

7

x' is x prime. x'' is x double prime.

answered Feb 20 '15 at 00:34

Esteemator

1,203

score 3 · Answer 2 · answered Feb 20 '15 at 00:41

$x$ dash is common in the UK for $x'$. So Brian is definitely not correct when he says "$x$ dash is definitely not correct". [Since I am in the US, I definitely hear $x$ prime primarily, though.] Griffin2000 does not say where he is.

Littlewood has a joke about this in his Miscellany. Derived sets in point-set topology are denoted like $E'$. Some mathematician was talking about something that would hold for such derived sets, and ended up saying "for any dashed set" ...

score 2 · Answer 3 · answered Feb 20 '15 at 00:46

x', x prime, is the first derivative of x and x'', x double prime, is the second derivative of x. I have never heard of x dash before, but I have see alternative versions of writing x' and x''. Almost two years ago, I had an ODE book that wrote $\dot x$ (first derivative) and $\ddot x$ (second derivative). It was strange, but eventually I got used to its meaning.

How do you pronounce x' and x''?

3 Answers3