The question is:

If one of the roots of x<sup>2</sup> + ax + 4 = 0 is twice the other root, then the value of 'a' is?

(A) -3(2)<sup>0.5</sup>

(B) 8(2)<sup>0.5</sup>

(C) (2)<sup>0.5</sup>

(D) -2(2)<sup>0.5</sup>

I have no idea what to do...please help.