# Basic question about dividing fractions of functions

**URL:** <https://boards.straightdope.com/t/basic-question-about-dividing-fractions-of-functions/743689>\
**Category:** Factual Questions\
**Created:** [January 20, 2016, 5:46pm UTC](https://boards.straightdope.com/t/basic-question-about-dividing-fractions-of-functions/743689 "2016-01-20T17:46:13Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\
**Post date:** [January 22, 2016, 7:35pm UTC](https://boards.straightdope.com/t/basic-question-about-dividing-fractions-of-functions/743689/21 "2016-01-22T19:35:13Z")

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> [@sbunny8](#):
>
> When in doubt, clarify.

Absolutely.

> [@](#):
>
> No mathematician I know would look at a - b - c and think “left to right”. On the contrary, mathematicians are taught to see those subtraction symbols as adding negative numbers. For example, 3x - 4x - 2x is interpreted as (3)(x) + (-4)(x) + (-2)(x) and we can just as easily rearrange them in whatever order we choose by applying the commutative property of addition.

Well, the question is whether the “-” sign in front of “b - c” negates just the “b” or negates the entire “b - c”. And this is what “left to right” is meant to settle: it means to read this notation in the former way rather than the latter way.

But it is true that people, for whatever reason, very frequently write chained subtractions in this way, and very rarely write chained divisions in this way. If you see “a - b - c - d…”, you can be quite sure what is meant. If you see “a / b / c / d…” or “a ÷ b ÷ c ÷ d…”, you are dealing with a weirdo.

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**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\
**Post date:** [January 22, 2016, 7:41pm UTC](https://boards.straightdope.com/t/basic-question-about-dividing-fractions-of-functions/743689/22 "2016-01-22T19:41:22Z")

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(Again, the last post is facts about notation, convention, and human intentions, and not facts about mathematical substance.)

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