A radical may be defined as a positive irrational number of the type 
, where the symbol 
is called the radical sign, the index n is called the order of the radical and x the radicand. A number can be a radical if and only if it is an irrational number and the radicand is a positive rational number. When the order is not mentioned it is taken as 2.
If two radicals have the same order and the same radicands in their reduced form they are called like radicals.
Addition and subtraction of radicals
Only like radicals can be added or subtracted by adding or subtracting their coefficients.
Example 1:
Example 2:
Multiplication of radicals
Radicals of different orders are first converted to same order by finding the LCM of orders of the given radicals and then multiplied using the rule 
SchoolTutoring Academy is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classes, and college. To learn more about how we help parents and students in Kitchener visit: Tutoring in Kitchener.