The non-negative (positive) square root of a number is called its Principal Square Root.
Every perfect square number has two square roots (positive and negative).
The concept of principal square root is only valid for positive real numbers and not valid for negative real numbers.
Square roots of 16 are + 4 and - 4.
4 is the positive square root of 16.
So, 4 is the principal square root of 16.
A. 8
B. - 8
C. - 4
D. 4
Correct Answer: A
Step 1: The positive square root of a number is called its principal square root.
Step 2: Square roots of 64 are + 8 and - 8.
Step 3: 8 is the positive square root of 64.
Step 4: So, 8 is the principal square root of 64.