Question

Which term of the sequence 5, 10, 20, 40, ... is
51202
(a) 10
(b) 11
(d) 14
(c) 12​

Answer 1

G.P=5,10,20.....5120

n th term = a* r^(n-1) = 5120 Here a= 5, r= 2

5*2^(n-1) = 5120

2^(n-1) = 5120/5 = 1024

2^(n-1) = 2^10

n = 11. Hence the right option is 6.

Answer 2

Step-by-step explanation:

a = 5 , r = 2

5*(2)^n-1 = 5120

(2)^n-1 = 1024

(2)^n-1 = (2)^10

n - 1 = 10

n = 11