The positive value of $\lambda$ for which the co-efficient of $x ^ { 2 }$ in the expansion $x ^ { 2 } \left( \sqrt { x } + \frac { \lambda } { x ^ { 2 } } \right) ^ { 10 }$ is 720, is (1) $\sqrt { 5 }$ (2) 3 (3) 4 (4) $2 \sqrt { 2 }$
The positive value of $\lambda$ for which the co-efficient of $x ^ { 2 }$ in the expansion $x ^ { 2 } \left( \sqrt { x } + \frac { \lambda } { x ^ { 2 } } \right) ^ { 10 }$ is 720, is\\
(1) $\sqrt { 5 }$\\
(2) 3\\
(3) 4\\
(4) $2 \sqrt { 2 }$