Answer
The conclusion: $\therefore$ $(3^{1/2})^6 = 3^{(1/2)\cdot 6} = 3^3$.
Work Step by Step
Universal modus ponens: ∀x, if P(x) then Q(x).
P(k) for a particular k.
∴Q(k).
In this case P(x) is: $\forall$ real numbers r, a, and b, if r is positive.
Q(x) is: $(r^a)^b = r^{ab}.$
k are the particular values for r, a, and b (3, 1/2, 6 respectively).
Therefore Q(k) is: $(3^{1/2})^6 = 3^{(1/2)\cdot 6} = 3^3$.