There are two words REAL AND NUMBER.we all of us know that there are various types of numbers like. 0.1.2.3
But what is the significance of word REAL.
That means if real word exist that means there should be another words that is called IMAGINARY.
square root of 2 is real number.
But square root of(-2)is imaginary number.
In class 10 you Will read only about only real number like 123,-1.-2.-3,0.1,0.2,root of 2
Imaginary number are like root of -2.they are denoted by (i) and square of i is -1.
I hope you are satisfied