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November 24th, 2017, 05:28 AM   #1
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Use 0 in rule of 3?

Hello! I'm doing a AHK script. If 0 does nothing, 1 doubles, what do I do with this: (16/9)/0=(14/9)/x?
The number 0 in rule of three screws it all. I just want to have 0 as a normal number. I tried changing 0 to 1 and then subtract 1 from x. It gave me -0,125. I don't know if it worked or if it's even correct, so what can I do?
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November 24th, 2017, 06:44 AM   #2
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You can't divide by zero.
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December 1st, 2017, 12:11 PM   #3
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I haven't seen the term "rule of three" in years- and then in a very old book!

The "rule of three" is an old term for a proportion- given any three of a, b, c, or d in $\displaystyle a:b::c:d$ or (in more modern notation) $\displaystyle \frac{a}{b}= \frac{c}{d}$, you can solve for the fourth.

$\displaystyle \frac{a}{b}= \frac{c}{d}$ can also be written as $\displaystyle \frac{b}{a}= \frac{d}{c}$, $\displaystyle \frac{a}{c}= \frac{b}{d}$ or even $\displaystyle ad= bc$.

As others have said, you cannot divide by 0 so it makes no sense to write "$\displaystyle \frac{16/9}{0}= \frac{14/9}{x}$" but that can be written as $\displaystyle \frac{0}{16/9}= \frac{x}{14/9}$ which reduces very quickly to x= 0. In fact, in order for "$\displaystyle \frac{A}{0}= \frac{B}{x}$" to make sense, for any A, B, we must have x= 0.
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