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The first term of a g.p is 7 and the last term is 448 . the sum is 889 calculate the common ratio

User Firkamon
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Answer:

Common ratio = 2

Step-by-step explanation:

The formula for nth term of a geometric progression is given as:

aₙ = arⁿ⁻¹

Given the following values

First term a = 7

r = unknown

n = unknown

Last term = nth term = aₙ = 448

Sum of the terms = 889

Substituting

448 = 7rⁿ⁻¹

Divide both sides by 7

rⁿ⁻¹ = 448/7

rⁿ⁻¹ = 64

Converting 64 to a power

rⁿ⁻¹ = 2⁶

Equating the powers together,

n - 1 = 6

n = 6+1 = 7

Number of terms (n) = 7

Therefore, the common ratio of the geometric progression( r ) = 2

User Juanpaulo
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