Answer
$$ - \frac{3}{2}{e^{2x}} + C$$
Work Step by Step
$$\eqalign{
& \int { - 3{e^{2x}}} dx \cr
& {\text{use multiple constant rule }}\int {k \cdot f\left( x \right)} dx = k\int {f\left( x \right)} dx \cr
& = - 3\int {{e^{2x}}} dx \cr
& {\text{use the indefinite integral of an exponential function formula }}\int {{e^{kx}}} dx = \frac{{{e^{kx}}}}{k} + C \cr
& = - 3\left( {\frac{{{e^{2x}}}}{2}} \right) + C \cr
& {\text{simplifying}} \cr
& = - \frac{3}{2}{e^{2x}} + C \cr} $$
