Evaluate the following.

let me know if its "Not a real number"

-√81

√-16

Step-by-step explanation:

(1)

-√81 = - 9 (although you could argue that it's ± 9, since 81 has two square roots: 9 and - 9). Real number.

(2) √ (-16) is imaginary, and the value is i·4 (or - i·4). Not a real number.

-9, Undefined

Step-by-step explanation:

-√81

-√9^2

-9