If ax3+bx2+cx+d is divisible by ax2+c,then a, b, c, d are in

Since, ax3+bx2+cx+d is divisible by ax2+c.Therefore, when ax3+bx2+cx+d is divided by al + c, the remainder is zero∴ d−bca=0⇒ bc=ad⇒ba=dc⇒a,b,c,d are in GP.