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Home » The sum of n terms of a progression is (2n – 1). Show that it is a GP and find its common ratio.
The sum of n terms of a progression is (2n – 1). Show that it is a GP and find its common ratio.
CBSE | Class 11 | Geometrical Progression | Maths | RS Aggarwal
The sum of n terms of a progression is (2n – 1). Show that it is a GP and find its common ratio.

Answer : In this question, we will try to rewrite the given sum of the progression like the formula for the sum a G.P. series.

It is given that Sn = ( 2n – 1)

The formula for the sum of a G.P. series is,By solving the 2 equations together, we can say thatBy corresponding the numbers with the variables, we can conclude a = 1

r = 2

The G.P. series will therefore look like ⇒ 1,2,4,8,16,……to n terms

∴ The given progression is a G.P. series with the common ration being 2.

 

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