Coulombs law problem

A charge of +q is located at the origin, while an identical charge is located on the x axis at x = 0.51 m. A third charge of +5q is located on the x axis at such a place that the net electrostatic force on the charge at the origin doubles, its direction remaining unchanged. Where should the third charge be located?

I worked this problem out as follows. Please point out if I go wrong.
F2=(kqq/.51^2)+(5kqq/x^2) which is equal to 2F1
2F1=(2kqq/.51^2)

So

(kqq/.51^2)=(5kqq/x^2)

So

1/(.51^2)=5/(x^2)

5(.51^2) =x^2

1.3005=x^2

x=1.14

Can somemone confirm this? I only have one more try on my homework.
Thanks

looks fine to me

perfectly alright i think