Which of the following is equivalent to 18 - √25?

5i

18 - 5i

18 + 5i

23

In this complex number, assuming that the equation actually is 18 - √-25, the real part is already simplified. However, the imaginary part can be simplified by taking out "i" from the root using the relation i = √-1. This is done below:

18 - √-25

18 - √ (-1) (25)

18 - 5i

From the choices, the correct answer is 18 - 5i.