To rationalize a fraction,you should eliminate the radical* sign from it's denominator,and to do that you should multiply that fraction's numerator and denominator by a polynomial or a number that can elminate the radical;for example:if the denominator of the fraction is radical2,you should multiply the numerator and denominator of that fraction by radical 2 so that the denominator will become 2...
(Radical*:a mathematical sign used to reduce a number to its square root)