Irrational numbers are those numbers whose denominators and in square root forms. We can express the numbers in lowest terms by taking out divisible perfect square numbers out of the square root sign. In this case, the rules applicable is that the simplest forms are those forms in which the variables degree is less than to the nth root. The numbers inside the roots should be divisible to the nth power of a number.
In this case, 125 is not divisible than any 6th root. The only other variable that can be 6th root is y^9 and x^6. hence the answer is
yz 6th root of (125x^3y^3)