Correct option is (C) -3√2

Let \(\alpha\;and\;2\alpha\) are roots of \(x^2+ax + 4 = 0\)   _______________(1)

\(\therefore\) Product of roots = 4

\(\Rightarrow\) \(2\alpha^2=4\)

\(\Rightarrow\) \(\alpha^2=2\)

\(\Rightarrow\) \(\alpha=\pm\sqrt2\)         ______________(2)

And sum of roots = -a

\(\therefore\) \(-a=\alpha+2\alpha\)

\(=3\alpha\)

\(=3(\pm\sqrt2)\)      (From (2))

\(=\pm3\sqrt2\)

\(\therefore a=\mp3\sqrt2\)

Possible values of a are \(3\sqrt{2}\;or\;-3\sqrt{2}.\)

Correct option is C) -3√2