Which condition makes x3+ax2+bx+cx^3+ax^2+bx+cx3+ax2+bx+c have roots in geometric progression?
a3c=b3a^3c = b^3a3c=b3
ac3=b3ac^3 = b^3ac3=b3
ac=b2ac = b^2ac=b2
c=abc = abc=ab