Is the power of 1/2 same thing as principal square root? $\sqrt{9} = 3$
9 has 2 square roots: 3 and -3.
What is $9^\frac12$? Is $9^\frac12 = \sqrt{9} = 3$ or is $9^\frac12 = \pm3$?

This previous answer of mine talks about the fact there are actually multiple exponentiation operators. The meaning of $9^{\frac{1}{2}}$ depends on which one you are actually using.
