Given P(x)=x3+ax2+bx+cP(x) = x^3 + ax^2 + bx + cP(x)=x3+ax2+bx+c has roots α,β,γ\alpha, \beta, \gammaα,β,γ in geometric progression, which condition must hold?
b3=ac3b^3 = ac^3b3=ac3
c3=a3bc^3 = a^3bc3=a3b
b3=a3cb^3 = a^3cb3=a3c
a2=ba^2 = ba2=b