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Why do all school algebra texts define simplest form for expressions with radicals to not allow a radical in the denominator. For the classic example, $1/\sqrt{3}$ needs to be "simplified" to $\sqrt{3}/3$.

Is there a mathematical or other reason?

And does the same apply to exponential notation -- are students expected to "simplify" $3^{-1/2}$ to $3^{1/2}/3$ ?

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    Where is this? Pretty silly to enforce such rules, IMO.2011-03-09
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    My schooling up until university required the same; and I never really understood it. The best explanation I could think of is that it is intuitively simpler to divide by an integer than an irrational; and they wanted us to think of things that way. But they had no problem dividing by π.....2011-03-09
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    My Theory: There is no longer any good reason to do so.2011-03-10
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    This is a duplicate, but I can't figure out how to find the original.2011-03-10
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    I've added a new answer, with a little bit on why canonical forms generally are used. When you learned how to reduce fractions to lowest terms, you were learning a canonical form. This is another.2012-06-13

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