What is the coefficient of $x$ in the expansion of $\left( 2 x + \frac { 1 } { 2 x } \right) ^ { 7 }$? [3 points] (1) 14 (2) 28 (3) 42 (4) 56 (5) 70
What is the coefficient of $x$ in the expansion of $\left( 2 x + \frac { 1 } { 2 x } \right) ^ { 7 }$? [3 points]\\
(1) 14\\
(2) 28\\
(3) 42\\
(4) 56\\
(5) 70