In a geometric sequence dividing any term by the term before it yields the common multiplier. Then x/(x+8) = (3x-8)/x Solving for x: reduces to x^2-10x +16 factor into (x-2)(x-8) Then x = 2 or 8 2 produces a sequence of -2, 2, -2 ... 8 produces a sequence of 4, 8, 16 ...