if 4,2x-4,......,64,21x+2 are the terms of GP . find the value of x ?

Answer 1

if GP , then
(2x-4)/4 = (21x+2)/64
128x-256 = 84x + 8
44x = 264
x = 6

check:
4, 8, ... , 64, 128

YUP, common ratio of 2