How many terms of the series 2 + 6 + 18 + …. Must be taken to make the sum equal to 728?

Asked by Sakshi | 1 year ago |  62

##### Solution :-

Given:

Sum of GP = 728

Where, a = 2, r = $$\dfrac{6}{2}$$ = 3, n = ?

By using the formula,

Sum of GP for n terms =

728 = $$\dfrac{ 2 (3^n – 1)}{(3-1)}$$

728 =$$\dfrac{ 2 (3^n – 1)}{2}$$

728 = 3n – 1

729 = 3n

36 = 3n

6 = n

6 terms are required to make a sum equal to 728

Answered by Sakshi | 1 year ago

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