If x,2x+2, and 3x+3 are first three terms of a G.P. then the fourth term is

x,2x+2,3x+3 are in G.P. Hence (2x+2)2=x(3x+3)⇒4x2+8x+4=3x2+3x⇒x2+5x+4=0⇒x=−1,−4 So, the G.P is −4,−6,−9,… (considering x=−4, as for x=−1,2x+2=0 )  Hence, the fourth term is −9×1.5=−13.5