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Use the geometric sequence to help write a recursive rule and an explicit rule for any geometric sequence. for general rules, the values are of n and consecutive integers starting with 1.

Use the geometric sequence to help write a recursive rule and an explicit rule for-example-1

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Question: Use the geometric sequence to help write a recursive rule and an explicit rule for any geometric sequence:

Solution:

A geometric sequence is a sequence of numbers in which the ratio between consecutive terms is constant. Remember that the constant factor (ratio) between consecutive terms of a geometric sequence is called the common ratio. Now, given a geometric sequence with the first term a1 and the common ratio r, the nth (or general) term is given by:


a_n\text{ = }a_1r^(n-1)

Thus, in this case, the common ratio r is:


r\text{ = }(10)/(5)\text{ = 2}

On the other hand, the first term of the sequence is a1 = 5. Then, we can conclude that the explicit rule for the given sequence is:


a_{n\text{ }}=5(2)^(n-1)

this is equivalent to:


a_{n\text{ }}=5.2^n.2^(-1)

this is equivalent to:


a_{n\text{ }}=(5)/(2).2^n

Then, the correct answer is:

The general rule:


a_{n\text{ }}=(5)/(2).2^n

the recursive rule:


a_1=\text{ 5}


a_{n\text{ }}=(5)/(2).2^n

Use the geometric sequence to help write a recursive rule and an explicit rule for-example-1
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