Question

Which of the following is a complex number?

Answer 1

Complex numbers emerge when you take the square root of a negative number, since the imaginary unit
`i` is defined by the relation
`i^2=-1`, which implies
`√(-1)=i`

The only option involving the square root of a negative number is the last one.

Answer 2

option D

Explanation:

Complex number is a number that has negative under the square root.

Square root (-1) =i is a complex number

square root of a negative number is a complex.

First option does not have any negative number under the square root so it is not a complex.

second option also not have negative number under square root . So it is not a complex

third option have positive 7 under the square root so it is not a complex

Fourth option have -9/5 under the square root . So it is a complex number