Q77. If $y = y ( x )$ is the solution of the differential equation $\frac { \mathrm { d } y } { \mathrm {~d} x } + 2 y = \sin ( 2 x ) , y ( 0 ) = \frac { 3 } { 4 }$, then $y \left( \frac { \pi } { 8 } \right)$ is equal to:\\
(1) $\mathrm { e } ^ { \pi / 8 }$\\
(2) $e ^ { \pi / 4 }$\\
(3) $e ^ { - \pi / 4 }$\\
(4) $e ^ { - \pi / 8 }$