What is the defenition of surd and its types?
According to Wordnik, a surd is a root that can not be written as a rational number, i.e. as a ratio of two numbers like 3/1 or 2/7. They can be classified according to the power of the root. A number under a square root would be a quadratic surd, one using a cube root would be cubic surd, and one with an nth root would be a surd of order n. For example, the square root of 2 would be a quadratic surd, because it can not be reduced to a rational number, and the number on the “root” is two.
