Before we move on to CERTS, let's look at a few terminologies. Consider the nth root of A. N is called the order or the index.
So when we are taking the cube root, the order will be 3. This root sign we see is called the radical. And the number under the radical is called the radicand or the base. This number is said as the nth root of A.
In the previous video, we saw what irrational root of a positive rational number means. Numbers like square root of 3 or the cube root of 5. The answer we got is irrational and the base is a positive rational number. So the irrational root of a positive rational number is called a SERD. These examples are SERDs. Remember the answer has to be irrational and the radicand or the base has to be positive rational number.
It means that square root of 4 or the cube root of 8 are not thirds as they result in rational numbers. Now let's look at the basic classification. How are real numbers classified?
It's simple. They are classified into two types. Rational and irrational numbers. Within irrational numbers, we have numbers like square root of 2, cube root of 7, square root of 5. And then there is another section of irrational numbers. Other special numbers like pi and e which is the Euler's number.
This category of irrational numbers are called CERDS. There is a common misunderstanding that all irrational numbers are CERDS but that's incorrect. Remember only a irrational root of a positive rational number is a CERD.