Question

How many terms are there in the gp 5,20,80,320,.....20480?

Answer 1

Answer:

Step-by-step explanation:

a=5

r=20/5=4

r=80/20=4

general term = arⁿ⁻¹

=>last term = 20480

so putting this in the equation we get,

=> 20480 = arⁿ⁻¹

=> 20480 = (5)(4)ⁿ⁻¹

=> 4ⁿ⁻¹=4096

=> 4ⁿ/4 = 4096

=> 4ⁿ = 4096/4

=> 4ⁿ = 1024

=> 4ⁿ = 2¹⁰

=> 4ⁿ = 4⁵

=> n=5....

i hope i have helped you somehow..

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