Question 1156701
adjacent terms have the same ratio
so (2a+2)/(2a-2)=(5a+1)/(2a+2)
Therefore,
4a^2+8a+4=10a^2-8a-2
so 0=6a^2-16a-6
or 3a^2-8a-3=0
(3a+1)(a-3)=0
a=3, or -1/3
the terms are 4, 8, 16 with common ratio 2  or -8/3, 4/3, -2/3 with  common ratio -1/2
a, ar, ar^2,...or 
4*2^r for r>=0
(-1)^r*(8/3)*(1/2)^(r-1) for r=1, 2,3,...