Since 2x-1 is a factor of f, x=1/2 is a zero, because 2x-1=0, 2x=1, x=1/2.
Synthetic division will help to find other factors:
1/2 | 30...7 -39 14
........30 15..11 14
........30 22 -28 | 0
The quotient is 30x^2+22x-28 so f(x)=(x-1/2)(30x^2+22x-28)=(2x-1)(15x^2+11x-14).
k=1/2 and q(x)=30x^2+22x-28.
We now look at factorising 15x^2+11x-14=(3x-2)(5x+7) so f(x)=(2x-1)(3x-2)(5x+7).