Question

what are imaginary numbers and how to find them

Answer 1

Numbers that are equal to the product of a real number and the square root of -1

Answer 2

An imaginary number is a complex number that can be written as a real number multiplied by the imaginary number i, which is defined by its property i2 = −1. The square of an imaginary number bi is −b2.
For example, 5i is an imaginary number, and its square is −25. Zero is considered to be both real and imaginary.