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Writing Mathematical Symbols in 20th century

Documents like the one you linked to were not typed on a typewriter. When writing on typewriters, it was common to leave some space in the document in which the formulas could be inserted by hand. ...
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Writing Mathematical Symbols in 20th century

It is really funny to read that in the beginning of 21-st century, some young people may think that journals and books printing had something to do with typewriters:-) If you look attentively at the ...
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Why did angular momentum get the letter L

I just want to comment that the agreement on letters, by which we write $\frac d{dt}\mathbf L=\mathbf M$ for the law of angular momentum, must have come very late -- after 1964. As evidence, note that ...
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Why are X and Y commonly used as mathematical placeholders?

See Earliest uses of mathematical symbols, which quotes F. Cajori, A History of Mathematical Notations, 2 volumes (1928-29) The use of z, y, x ... to represent unknowns is due to René Descartes, ...
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Why is American and French notation different for open intervals (x, y) vs. ]x, y[?

Notation $()$ is traditional, and $].[$ was introduced by Bourbaki. Much of the Bourbaki notations and terminology became standard, but English speaking people are the most conservative ones in this ...
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Who invented the Leibnitz notation $\frac{d^2y}{dx^2}$ for the *second* derivative?

Leibniz did use this notation for instance in his paper Supplementum geometriae practicae, Acta Eruditorum, April 1693, p. 179 (Google Books link):
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When was the first recorded use of subscript in mathematics to represent index?

Looking in Mathsym, I find: $\bullet \;$Use of $\;{}^1a,\;{}^2a,\;{}^3a$ in Laplace, 1772. Histoire de l'Académie royale des sciences, p. 294 It didn't catch on. $\bullet \;$Then Cauchy, 1815, with ...
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What was Euler's motivation for introducing $i$ for $\sqrt{-1}$?

According to Florian Cajori, A History of Mathematical Notations (1928 - Dover reprint), Vol II, page 128 : 498. It was Euler who first used the letter $i$ for $\sqrt{-1}$. He gave it in a memoir ...
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How did mathematicians notate the empty set before $\varnothing$?

George Boole introduced the concept of empty set, or "nothing" as he called it, as the complement to the "universe" in his Mathematical Analysis of Logic (1847). His notations for ...
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Why is the radical symbol $\sqrt{}$ called "radical"?

"Radical" comes from Latin "radicalis", having roots, an equivalent "radix" was also commonly used earlier. While Rudolff did use the radix in 1525 his did not have the overbar on top, now called ...
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When did it become understood that irrational numbers have non-repeating decimal representations?

Before approximating roots Al-Samawal performs long division of 210 by 13 to five decimal places, not enough to notice that digits cycle after the sixth. And this is the problem with discovering it ...
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Why was delta ($\Delta$) chosen to represent change of a quantity?

There was a related question on Math.SE, which Mauro Allegranza answered with reference to Cajori's classic History of Mathematical Notations (v.II, p.205). It is a great source and is freely ...
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Is the symbol for set membership $\in$ derived from greek letter $\epsilon$?

Yes, it is. In Giuseppe Peano's Arithmetices Principia (1889), the $\epsilon$ symbol is explained as follows (page x): Signum $\epsilon$ significat est. [The sign $\epsilon$ means is.]...
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Who invented the way we write exponentiation?

Browsing the "original" historiographical" source for the "power" symbolisms , i.e. : Florian Cajori, A History of Mathematical Notations (1928, Dover reprint), page 335-on can be very istructive, ...
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This usage of $\mathbf i$, $\mathbf j$, and $\mathbf k$ is not specific to physics. It is also used in mathematics, specifically when teaching linear algebra or multivariable calculus in $\mathbf R^3$ ...