The key idea when rationalizing a denominator is to choose a way to multiply by a form of one, so this denominator ends up simplifying to something that doesn’t contain a radical. So, if we want to get the power of 4 up to the power of 6. We need to multiply it by two more factors of 2 inside of a cubed root. We have to use an index of three here since this is also an index of 3. If the indexes match, then we can multiply these radicants together to get 2 to the 4th times 2 squared, which is 2 to the 6th.