# How do you rationalize fractions

1. Jan 30, 2007

### afcwestwarrior

how do you do that

2. Jan 30, 2007

### eccefeles

Fractions are already rational. Here's what "rational" means: http://en.wikipedia.org/wiki/Rational_number" [Broken]

Last edited by a moderator: May 2, 2017
3. Jan 31, 2007

### arildno

Incorrect!
A "fraction" is a real number that is written as the product of one real number a (called the "numerator"), and the multiplicative inverse of a real (non-zero) number b (called the denominator).

To "rationalize" a fraction means to rewrite the denominator as a natural number, if possible.

Example:
$$\frac{1}{\sqrt{2}}=\frac{1}{\sqrt{2}}*1=\frac{1}{\sqrt{2}}*\frac{\sqrt{2}}{\sqrt{2}}=\frac{\sqrt{2}}{2}$$

Last edited by a moderator: May 2, 2017
4. Jan 31, 2007

### HallsofIvy

What does this have to do with calculus? I am moving it to "General Math".

5. Jan 31, 2007

### HallsofIvy

I've never heard of "realizing" a fraction! What language is that translated from? However, I will agree that one does not rationalize fractions!
The example arildno gave was rationalizing the denominator of a fraction. There are also times when one would want to rationalize the numerator of a fraction. In general, it is not possible to rationalize both numerator and denominator at the same time.

6. Jan 31, 2007

### eccefeles

My apologies! I've made a big fool of myself once again. I was thinking about "realising" as in making the denominator of a fraction (containing complex numbers) real! (I was taught this term back in high school, here in Australia.) arildno and Hallsofivy are absolutely correct.

I'm really sorry for wasting everyone's time. I think I should go back to lurking.

7. Feb 1, 2007

### arildno

I stand corrected.

8. Feb 1, 2007

### HallsofIvy

"realizing"! I like that. Reminds me of when, in an algebra class, we were learning about 'adding' an identity to a semigroup (to make it a monoid) and we had quite an argument about what the process should be called.

Suggestions were "unification", "one-ification" and "identification"!