Arithmetico-Geometric Series Definition : If each part of a series is the product of the terms of the terms of an arithmetic progression and the terms of a geometric progression, then the series is known as the Arithmetico-Geometric series. The terms of the arithmetic progression in the general form are:- a,a+d,a+2d,a+3d, ....... a+(n-1)d and The terms of a geometric progression are 1,r,r²,r³, ... then the series a.1+(a+d).r+(a+2d).r²+...............+a+(n-1)d.r^n is called the arithmetico-geometric series.