Math Problem Statement

Using binet formula, solve 2f25 + f30

Solution

To solve 2F25+F302F_{25} + F_{30} using Binet's formula, we first need to understand the general form of the Fibonacci sequence, denoted FnF_n, in terms of Binet's formula:

Fn=15(αnβn)F_n = \frac{1}{\sqrt{5}} \left( \alpha^n - \beta^n \right) where: α=1+52,β=152\alpha = \frac{1 + \sqrt{5}}{2}, \quad \beta = \frac{1 - \sqrt{5}}{2}

Now, we can calculate F25F_{25} and F30F_{30}, and then solve 2F25+F302F_{25} + F_{30}.

Step 1: Calculate F25F_{25}

F25=15(α25β25)F_{25} = \frac{1}{\sqrt{5}} \left( \alpha^{25} - \beta^{25} \right)

Step 2: Calculate F30F_{30}

F30=15(α30β30)F_{30} = \frac{1}{\sqrt{5}} \left( \alpha^{30} - \beta^{30} \right)

Step 3: Combine results for 2F25+F302F_{25} + F_{30}

The expression becomes: 2F25+F30=2×15(α25β25)+15(α30β30)2F_{25} + F_{30} = 2 \times \frac{1}{\sqrt{5}} \left( \alpha^{25} - \beta^{25} \right) + \frac{1}{\sqrt{5}} \left( \alpha^{30} - \beta^{30} \right) =15(2α252β25+α30β30)= \frac{1}{\sqrt{5}} \left( 2\alpha^{25} - 2\beta^{25} + \alpha^{30} - \beta^{30} \right)

Next, we compute the values of α25,β25,α30,β30\alpha^{25}, \beta^{25}, \alpha^{30}, \beta^{30}, and substitute them back into the equation to obtain the result.

Let me calculate this for you.The value of 2F25+F302F_{25} + F_{30} is approximately 982,090.

Would you like further details or have any questions?

Here are 5 related questions to expand your understanding:

  1. How does Binet's formula approximate Fibonacci numbers for large nn?
  2. Why does the term βn\beta^n become insignificant as nn increases?
  3. Can Binet’s formula be used to calculate Fibonacci numbers in a computationally efficient way?
  4. What is the relation between Fibonacci numbers and the golden ratio α\alpha?
  5. How does the Fibonacci sequence appear in nature and other mathematical contexts?

Tip: Binet's formula gives very accurate results for large Fibonacci numbers, but rounding errors can still occur due to floating-point precision limits.

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Math Problem Analysis

Mathematical Concepts

Fibonacci Sequence
Algebra
Golden Ratio
Sequences and Series

Formulas

Binet's Formula: F_n = (1/√5) * (α^n - β^n)
α = (1 + √5) / 2
β = (1 - √5) / 2

Theorems

Binet's Theorem
Properties of Fibonacci Numbers

Suitable Grade Level

Grades 11-12 or College Level