The nth root of a fraction

The nth root of a fraction is sometimes easier to evaluate by taking the nth root of the numerator and denominator separately. sqrt(64/27)=sqrt(64)/sqrt(27)=4/3 This rule yields for all real numbers where the denominator is not 0. However, in order to avoid non-real solutions it is necessary that the numerator and the denominator are non-negative numbers when n is an even number.