If z is the principal square root of 8, what must be true? If z is the principal square root of 8, what must be true?

A. z = 82, and z is positive

B. z = 82, and z is negative

C. z2 = 8, and z is negative

D. z2 = 8, and z is positive

If z is the principal square root of 8, this means that if we take the square of z, then the answer would reversibly be equal to 8. In this case, the answers would be both c and d. The square of a positive number is a positive number while the square of a negative number still renders a positive number. The answer hence is D.