The order of terms matters even when they commute: Difference between revisions
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[[Category:Inconsistencies]] | [[Category:Inconsistencies]] | ||
When writing | When writing an expression that consists of several terms, the conventions regarding their order appear arbitrary. | ||
==Multiplication== | |||
It is usual to write: | |||
* \(xy\) and \(yx\) in either order; | * \(xy\) and \(yx\) in either order; | ||
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* \(x\sqrt{2}\) but not \(\sqrt{2}x\) (to avoid confusion with \(\sqrt{2x}\)). (See [[Something on the right of a radical]]) | * \(x\sqrt{2}\) but not \(\sqrt{2}x\) (to avoid confusion with \(\sqrt{2x}\)). (See [[Something on the right of a radical]]) | ||
* \(\sqrt{2}\sin x\) but not \(\sin x \sqrt{2}\) (to avoid confusion with \(\sin \left(x\sqrt{2}\right)\)). | * \(\sqrt{2}\sin x\) but not \(\sin x \sqrt{2}\) (to avoid confusion with \(\sin \left(x\sqrt{2}\right)\)). | ||
==Addition== | |||
People sometimes rearrange a sum to avoid a leading unary minus, even when this contradicts the convention of writing terms in decreasing order of degree: | |||
\[ 1 - x \] | |||
instead of | |||
\[ -x + 1 \] | |||
Revision as of 09:39, 15 July 2021
When writing an expression that consists of several terms, the conventions regarding their order appear arbitrary.
Multiplication
It is usual to write:
- \(xy\) and \(yx\) in either order;
- \(5t\) but not \(t5\) (to avoid confusion with \(t_5\) or \(t^5\));
- \(x\sqrt{2}\) but not \(\sqrt{2}x\) (to avoid confusion with \(\sqrt{2x}\)). (See Something on the right of a radical)
- \(\sqrt{2}\sin x\) but not \(\sin x \sqrt{2}\) (to avoid confusion with \(\sin \left(x\sqrt{2}\right)\)).
Addition
People sometimes rearrange a sum to avoid a leading unary minus, even when this contradicts the convention of writing terms in decreasing order of degree:
\[ 1 - x \]
instead of
\[ -x + 1 \]
