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The common ratio, r, in a geometric sequence whose second term is

24 and whose fifth term is 1536

1 Answer

3 votes

Answer:

r = 4

Explanation:

The general term of the geometric sequence is ⇒ an = a * rⁿ⁻¹

Where a is the first term and r is the common ratio

The second term is 24 ⇒ 24 = a * r²⁻¹ = a r ⇒(1)

The fifth term is 1536 ⇒ 1536 = a * r⁵⁻¹ = a r⁴ = (a r) * r³ ⇒ (2)

By substitution with the value of (a r) from eq.(1) at eq.(2)

So, 1536 = 24 r³

∴ r³ = 1536/24 = 64

∴ r = ∛64 = 4

so, the common ratio r = 4

And the first term = 24/4 = 6

The geometric sequence will be ⇒ an = 6 * 4ⁿ⁻¹

User Paul Ghiran
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