Answer
$\displaystyle \frac{6(2x+1)}{x^{3/2}}$
Work Step by Step
Manipulating exponents, we find that $ A^{-1/2}=A^{-3/2+1}=A^{-3/2}\cdot A^{1}$
We can factor our $6x^{-3/2}$.
$12x^{-1/2}+6x^{-3/2}=6x^{-3/2}(2x+1)$
If we want all positive exponents, we apply $ a^{-n}=\displaystyle \frac{1}{a^{n}}$
= $\displaystyle \frac{6(2x+1)}{x^{3/2}}$
