JEE Advance - Mathematics (2002 - No. 23)
If $${a_1},{a_2}.......,{a_n}$$ are positive real numbers whose product is a fixed number c, then the minimum value of $${a_1} + {a_2} + ..... + {a_{n - 1}} + 2{a_n}$$ is
$$n{(2c)^{1/n}}$$
$$(n + 1){c^{1/n}}$$
$$2n{c^{1/n}}$$
$$(n + 1)\,{(2c)^{1/n}}$$