Find the Sum of n terms of Geometric Sequence a = 4, n = 8, and r =3

Steps to find sum of n terms of geometric sequence:

sum of n terms of geometric sequence formula:-

S_n = `a*(r^n-1)/(r-1)`

where:

• s_n is the sum of n terms
• a is first term
• n is total number of terms
• r is common ratio

Input values are:-

a = 4

n = 8

r = 3

Put values into formula

S₈ = `a*(r^n-1)/(r-1)`

S₈ = `4*(3^8-1)/(3-1)`

S₈ = 13120.0

Follow the detailed steps listed below to find the Sum of n terms of Geometric Sequence a = 4, n = 8, and r = 3 to make your calculations faster.

• The initial step is to find out the First Term of Sequence a = 4, Common Ratio r = 3 and n = 8
• Later, substitute the given values in the Sum of n terms in G.P Formula i.e. S_n = a[(r^n-1)/(r-1)] if r > 1 and r ≠ 1 or S_n = a[(1 – rⁿ)/(1 – r)] if r < 1 and r ≠ 1
• As in the given case common ratio r is greater than 1 we will use the formula Sn = a[(r^n-1)/(r-1)] and substitute given values i.e. S₆ = 4[(3^8-1)/(3-1)]
• Simplifying further we have the Sum of n terms of Geometric Sequence S6= 13120.0.

Example for Finding Sum of n terms of Geometric Sequence