If the first three terms of a geometric sequence are 8, 12, and 2x-4, then what is the value of x?

Question

I am thinking that the common ratio is 3/2, so the next  term has to be equal to 18, making 2x-4=18, making x = 11. correct?

Answer 1

These terms must have a common ratio, since geometric sequence.

 

r = 12 / 8 = 3 / 2

 

 

Then,

 

(2x - 4) / 12 = 3 / 2

 

 

Solve this equation for x.

Answer 2

12/8 = (2x-4)12

144 = 8(2x-4)

144 = 16x - 32

176 = 16x

11 = x