Radicals are considered like radicals if they have the same index and the same radicand. The index is the number that indicates the root being taken (e.g. square root, cube root), while the radicand is the number under the radical symbol. If two radicals have the same index and radicand, then they are like radicals. For example, √2 and √3 are like radicals because they both have a square root (index of 2) and their radicands are different (2 and 3).
