Question

Which term of the GP-2,4,-8,16,. is 256?

Answer 1

Answer:

a = -2

r = 4/-2 = -2

tn = a.(r)^n-1

tn = 256

256 = (-2)(-2)^n-1

256 = (-2)^n

reciprocal both sides

1/256 = 1/2^n

1/256 = (1/2)^n

(1/2)^n= (1/2)^8

n = 8