Question

3. How many terms are there in the G. P. 5. 20, 80,
5120
​

Answer 1

Step-by-step explanation:

Common ratio, r = 205

= 4

Last term or nth term of GP = arn - 1

20480 = 5 × (4n - 1)

Or, 4n - 1 = 204805

= 48

So, comparing the power,

Thus, n - 1 = 8

Or, n = 7

Number of terms = 7