Difference between arithematic and geometric sequnces derive the formula for summation of arithematic and geometric sequence Solution An arithmeticsequence is a sequence with the difference between twoconsecutive terms constant. The difference is called thecommondifference. A geometric sequence is a sequence with theratio between two consecutive terms constant. This ratio iscalled the commonratio Arithmeticformula: tn = t1 + (n -1)d tn is the nth term, t1 is the first term, andd is the commondifference. tn is the nth term, t1 is the first term, andd is the commondifference. Geometricformula: tn = t1. r(n -1) tn is the nth term, t1 is the first term,and r is the common ratio (hope this answers yourquery).