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"what is the sixth term when the first term is 4 and the common ratio is 3?" How do I write a rule and find the given term for this

User Phobie
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1 Answer

6 votes

Answer:

a6 = 972

Explanation:

Use the generic rule and fill in the values you are given:

an = a1·r^(n-1) . . . . . for first term a1 and common ratio r

You are told a1 = 4, r = 3, so your rule is ...

an = 4·3^(n-1)

To find the 6th term, evaluate this expression for n=6.

a6 = 4·3^(6-1) = 4·243 = 972

_____

Or, you can simply start with the given first term and calculate each term by multiplying the previous one by 3.

4, 12, 36, 108, 324, 972, ...

User Tj Kellie
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5.8k points