Answer
$= \frac{(3+12x^{2})}{2x^{3}}$
Work Step by Step
1) Multiply a fraction with the other denominator to obtain a common denominator between the two fractions. In this case, we only need to multiply the second fraction by $2x^{2}/2x^{2}$ to obtain a common denominator of $2x^{3}$
2) Add the fractions
$ = \frac{3}{2x^{3}} + \frac{6}{x}$
$ = \frac{3}{2x^{3}} + \frac{6(2x^{2})}{2x^{3}}$
$= \frac{3+12x^{2}}{2x^{3}}$
