Question

Which of the following expressions is equal to -x^2-36?

Answer 1

The correct  answer is the option "B":

 B.(-x-6i)(x-6i)

 Explanation

 You must keep in mind the following:

 1. By definition, a complex number has the following form:

  a+bi

 "a" is the real part and "b" is the imaginary part.

 2. i²=-1

 3. Then,you have:

 (-x-6i)(x-6i)=(-x²+(6i)²)=-x²-36

 4. Therefore, the answer is: (-x-6i)(x-6i)