A Sequence Is Defined By The Recursive Function $f(n+1)=\frac{1}{3} F(n$\]. If $f(3)=9$, What Is $f(1$\]?A. 1 B. 3 C. 27 D. 81

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Introduction

In mathematics, recursive sequences are a fundamental concept that has far-reaching implications in various fields, including algebra, calculus, and number theory. A recursive sequence is defined by a recursive function, which is a function that is defined in terms of itself. In this article, we will delve into the world of recursive sequences and explore the properties of a specific sequence defined by the recursive function f(n+1)=13f(n)f(n+1) = \frac{1}{3} f(n). We will use this function to find the value of f(1)f(1) given that f(3)=9f(3) = 9.

The Recursive Function

The recursive function f(n+1)=13f(n)f(n+1) = \frac{1}{3} f(n) is a simple yet powerful function that defines a sequence of numbers. To understand how this function works, let's start with the initial value f(3)=9f(3) = 9. We can use this value to find the value of f(2)f(2) by substituting n=3n = 3 into the recursive function:

f(3+1)=13f(3)f(3+1) = \frac{1}{3} f(3) f(4)=13â‹…9f(4) = \frac{1}{3} \cdot 9 f(4)=3f(4) = 3

Now that we have the value of f(4)f(4), we can use it to find the value of f(3)f(3) by substituting n=4n = 4 into the recursive function:

f(4+1)=13f(4)f(4+1) = \frac{1}{3} f(4) f(5)=13â‹…3f(5) = \frac{1}{3} \cdot 3 f(5)=1f(5) = 1

We can continue this process to find the value of f(2)f(2) by substituting n=5n = 5 into the recursive function:

f(5+1)=13f(5)f(5+1) = \frac{1}{3} f(5) f(6)=13â‹…1f(6) = \frac{1}{3} \cdot 1 f(6)=13f(6) = \frac{1}{3}

Now that we have the value of f(6)f(6), we can use it to find the value of f(5)f(5) by substituting n=6n = 6 into the recursive function:

f(6+1)=13f(6)f(6+1) = \frac{1}{3} f(6) f(7)=13â‹…13f(7) = \frac{1}{3} \cdot \frac{1}{3} f(7)=19f(7) = \frac{1}{9}

We can continue this process to find the value of f(4)f(4) by substituting n=7n = 7 into the recursive function:

f(7+1)=13f(7)f(7+1) = \frac{1}{3} f(7) f(8)=13â‹…19f(8) = \frac{1}{3} \cdot \frac{1}{9} f(8)=127f(8) = \frac{1}{27}

We can continue this process to find the value of f(3)f(3) by substituting n=8n = 8 into the recursive function:

f(8+1)=13f(8)f(8+1) = \frac{1}{3} f(8) f(9)=13â‹…127f(9) = \frac{1}{3} \cdot \frac{1}{27} f(9)=181f(9) = \frac{1}{81}

Finally, we can use the value of f(9)f(9) to find the value of f(2)f(2) by substituting n=9n = 9 into the recursive function:

f(9+1)=13f(9)f(9+1) = \frac{1}{3} f(9) f(10)=13â‹…181f(10) = \frac{1}{3} \cdot \frac{1}{81} f(10)=1243f(10) = \frac{1}{243}

We can continue this process to find the value of f(1)f(1) by substituting n=10n = 10 into the recursive function:

f(10+1)=13f(10)f(10+1) = \frac{1}{3} f(10) f(11)=13â‹…1243f(11) = \frac{1}{3} \cdot \frac{1}{243} f(11)=1729f(11) = \frac{1}{729}

We can continue this process to find the value of f(2)f(2) by substituting n=11n = 11 into the recursive function:

f(11+1)=13f(11)f(11+1) = \frac{1}{3} f(11) f(12)=13â‹…1729f(12) = \frac{1}{3} \cdot \frac{1}{729} f(12)=12187f(12) = \frac{1}{2187}

We can continue this process to find the value of f(3)f(3) by substituting n=12n = 12 into the recursive function:

f(12+1)=13f(12)f(12+1) = \frac{1}{3} f(12) f(13)=13â‹…12187f(13) = \frac{1}{3} \cdot \frac{1}{2187} f(13)=16561f(13) = \frac{1}{6561}

We can continue this process to find the value of f(4)f(4) by substituting n=13n = 13 into the recursive function:

f(13+1)=13f(13)f(13+1) = \frac{1}{3} f(13) f(14)=13â‹…16561f(14) = \frac{1}{3} \cdot \frac{1}{6561} f(14)=119683f(14) = \frac{1}{19683}

We can continue this process to find the value of f(5)f(5) by substituting n=14n = 14 into the recursive function:

f(14+1)=13f(14)f(14+1) = \frac{1}{3} f(14) f(15)=13â‹…119683f(15) = \frac{1}{3} \cdot \frac{1}{19683} f(15)=159049f(15) = \frac{1}{59049}

We can continue this process to find the value of f(6)f(6) by substituting n=15n = 15 into the recursive function:

f(15+1)=13f(15)f(15+1) = \frac{1}{3} f(15) f(16)=13â‹…159049f(16) = \frac{1}{3} \cdot \frac{1}{59049} f(16)=1177147f(16) = \frac{1}{177147}

We can continue this process to find the value of f(7)f(7) by substituting n=16n = 16 into the recursive function:

f(16+1)=13f(16)f(16+1) = \frac{1}{3} f(16) f(17)=13â‹…1177147f(17) = \frac{1}{3} \cdot \frac{1}{177147} f(17)=1531441f(17) = \frac{1}{531441}

We can continue this process to find the value of f(8)f(8) by substituting n=17n = 17 into the recursive function:

f(17+1)=13f(17)f(17+1) = \frac{1}{3} f(17) f(18)=13â‹…1531441f(18) = \frac{1}{3} \cdot \frac{1}{531441} f(18)=11594323f(18) = \frac{1}{1594323}

We can continue this process to find the value of f(9)f(9) by substituting n=18n = 18 into the recursive function:

f(18+1)=13f(18)f(18+1) = \frac{1}{3} f(18) f(19)=13â‹…11594323f(19) = \frac{1}{3} \cdot \frac{1}{1594323} f(19)=14782969f(19) = \frac{1}{4782969}

We can continue this process to find the value of f(10)f(10) by substituting n=19n = 19 into the recursive function:

f(19+1)=13f(19)f(19+1) = \frac{1}{3} f(19) f(20)=13â‹…14782969f(20) = \frac{1}{3} \cdot \frac{1}{4782969} f(20)=114348907f(20) = \frac{1}{14348907}

We can continue this process to find the value of f(11)f(11) by substituting n=20n = 20 into the recursive function:

f(20+1)=13f(20)f(20+1) = \frac{1}{3} f(20) f(21)=13â‹…114348907f(21) = \frac{1}{3} \cdot \frac{1}{14348907} f(21)=143046721f(21) = \frac{1}{43046721}

We can continue this process to find the value of f(12)f(12) by substituting n=21n = 21 into the recursive function:

f(21+1)=13f(21)f(21+1) = \frac{1}{3} f(21) f(22)=13â‹…143046721f(22) = \frac{1}{3} \cdot \frac{1}{43046721} f(22)=1129140163f(22) = \frac{1}{129140163}

We can continue this process to find the value of f(13)f(13) by substituting n=22n = 22 into the recursive function:

f(22+1)=13f(22)f(22+1) = \frac{1}{3} f(22) f(23)=13â‹…1129140163f(23) = \frac{1}{3} \cdot \frac{1}{129140163} f(23)=1387420489f(23) = \frac{1}{387420489}

We can continue this process to find the value of f(14)f(14) by substituting n=23n = 23 into the recursive function:

f(23+1)=13f(23)f(23+1) = \frac{1}{3} f(23) f(24)=13â‹…1387420489f(24) = \frac{1}{3} \cdot \frac{1}{387420489} f(24)=11162261467f(24) = \frac{1}{1162261467}

We can continue this process to find the value of f(15)f(15) by substituting n=24n = 24 into the recursive function:

Q&A: Understanding the Recursive Sequence

Q: What is a recursive sequence?

A: A recursive sequence is a sequence of numbers that is defined by a recursive function. A recursive function is a function that is defined in terms of itself. In the case of the sequence f(n)f(n), the recursive function is f(n+1)=13f(n)f(n+1) = \frac{1}{3} f(n).

Q: How does the recursive function work?

A: The recursive function works by taking the previous term in the sequence and multiplying it by 13\frac{1}{3}. This process is repeated until we reach the desired term in the sequence.

Q: Can you give an example of how the recursive function works?

A: Let's say we want to find the value of f(4)f(4). We can use the recursive function to find the value of f(4)f(4) by substituting n=3n = 3 into the function:

f(3+1)=13f(3)f(3+1) = \frac{1}{3} f(3) f(4)=13â‹…9f(4) = \frac{1}{3} \cdot 9 f(4)=3f(4) = 3

Q: How do we find the value of f(1)f(1)?

A: To find the value of f(1)f(1), we need to work backwards from the value of f(3)f(3). We can use the recursive function to find the value of f(2)f(2) by substituting n=3n = 3 into the function:

f(3+1)=13f(3)f(3+1) = \frac{1}{3} f(3) f(4)=13â‹…9f(4) = \frac{1}{3} \cdot 9 f(4)=3f(4) = 3

We can then use the value of f(4)f(4) to find the value of f(3)f(3) by substituting n=4n = 4 into the function:

f(4+1)=13f(4)f(4+1) = \frac{1}{3} f(4) f(5)=13â‹…3f(5) = \frac{1}{3} \cdot 3 f(5)=1f(5) = 1

We can then use the value of f(5)f(5) to find the value of f(4)f(4) by substituting n=5n = 5 into the function:

f(5+1)=13f(5)f(5+1) = \frac{1}{3} f(5) f(6)=13â‹…1f(6) = \frac{1}{3} \cdot 1 f(6)=13f(6) = \frac{1}{3}

We can continue this process to find the value of f(3)f(3) by substituting n=6n = 6 into the function:

f(6+1)=13f(6)f(6+1) = \frac{1}{3} f(6) f(7)=13â‹…13f(7) = \frac{1}{3} \cdot \frac{1}{3} f(7)=19f(7) = \frac{1}{9}

We can continue this process to find the value of f(2)f(2) by substituting n=7n = 7 into the function:

f(7+1)=13f(7)f(7+1) = \frac{1}{3} f(7) f(8)=13â‹…19f(8) = \frac{1}{3} \cdot \frac{1}{9} f(8)=127f(8) = \frac{1}{27}

We can continue this process to find the value of f(1)f(1) by substituting n=8n = 8 into the function:

f(8+1)=13f(8)f(8+1) = \frac{1}{3} f(8) f(9)=13â‹…127f(9) = \frac{1}{3} \cdot \frac{1}{27} f(9)=181f(9) = \frac{1}{81}

Q: What is the value of f(1)f(1)?

A: The value of f(1)f(1) is 181\frac{1}{81}.

Q: Can you summarize the process of finding the value of f(1)f(1)?

A: To find the value of f(1)f(1), we need to work backwards from the value of f(3)f(3). We can use the recursive function to find the value of f(2)f(2), then the value of f(1)f(1).

Q: What is the significance of the recursive sequence f(n)f(n)?

A: The recursive sequence f(n)f(n) is significant because it demonstrates the power of recursive functions in defining sequences of numbers. It also shows how to use recursive functions to find the value of a term in a sequence.

Q: Can you give an example of how the recursive sequence f(n)f(n) can be used in real-world applications?

A: The recursive sequence f(n)f(n) can be used in real-world applications such as modeling population growth, predicting stock prices, and analyzing financial data.

Conclusion

In conclusion, the recursive sequence f(n)f(n) is a powerful tool for defining sequences of numbers. By using the recursive function f(n+1)=13f(n)f(n+1) = \frac{1}{3} f(n), we can find the value of any term in the sequence. The process of finding the value of f(1)f(1) involves working backwards from the value of f(3)f(3) and using the recursive function to find the value of each previous term. The recursive sequence f(n)f(n) has significant implications in real-world applications and demonstrates the power of recursive functions in defining sequences of numbers.