#1**+1 **

17

5th term = 140

7th term = 35

We have that

(140)r^2 = (35) where r is the common ratio

Divide both sides by 140

r^2 = 35/140 = 1/4 take both roots

r = +/- sqrt (1/4) = +/- 1/2

So....note that the 6th term could be (140)(1/2) = 70

Or.....the 6th term could be (140) (-1/2) = -70

Thus..... ± 70 is correct

CPhill
May 17, 2018