Find the Derivative of the Function $f ( x ) = \frac { x ^ { 3 } + 6 x } { 3 }$

Multiple Choice

Find the derivative of the function $f ( x ) = \frac { x ^ { 3 } + 6 x } { 3 }$ .

A) $f ^ { \prime } ( x ) = x ^ { 2 } + 2$
B) $f ^ { \prime } ( x ) = x ^ { 2 } + 6$
C) $f ^ { \prime } ( x ) = x ^ { 2 } + 2 x$
D) $f ^ { \prime } ( x ) = x ^ { 2 } + x$
E) $f ^ { \prime } ( x ) = x ^ { 2 } - 2 x$