For the function $f ( x ) = 2 x ^ { 2 } + a x$, when $\lim _ { h \rightarrow 0 } \frac { f ( 1 + h ) - f ( 1 ) } { h } = 6$, what is the value of the constant $a$? [3 points] (1) $-4$ (2) $-2$ (3) $0$ (4) $2$ (5) $4$
For the function $f ( x ) = 2 x ^ { 2 } + a x$, when $\lim _ { h \rightarrow 0 } \frac { f ( 1 + h ) - f ( 1 ) } { h } = 6$, what is the value of the constant $a$? [3 points]\\
(1) $-4$\\
(2) $-2$\\
(3) $0$\\
(4) $2$\\
(5) $4$