What do you mean by rationalizing it? You talk about rationalizing fractions but you mean rationalizing the numerator or denominator- you can't just change an irrational number to a rational number. If you change the denominator of a fraction from an irrational number to a rational number, the numerator has to become irrational.
If you mean "rationalize the denominator" in , okay- multiply numerator and denomonator by ! That gives the fraction . Of course, that is still equal to - you're not changing the whole number so it is still irrational but now the numerator is irrational, and the denominator, 1, is rational.