Real Numbers
The sum or difference of a rational number and an irrational number is an irrational number,
The product or quotient of a non-zero rational number with an irrational number is irrational.
If we add, subtract, multiply or divide two irrational numbers we may or may not get an irrational number,
To rationalize the denominator of 1/ a+b root x, we multiply it by a -b root x / a - b root x where 'a' and 'b' are integers.
To rationalize the denominator of root x + root y , we multiply it by root x - root y / root x - root y.