Math Problem Statement

using Binet's formula, find F35/5

Solution

To find F355\frac{F_{35}}{5} using Binet's Formula, we can proceed as follows:

Binet's Formula for Fibonacci numbers:

Fn=15(αnβn)F_n = \frac{1}{\sqrt{5}} \left( \alpha^n - \beta^n \right) where:

  • α=1+52\alpha = \frac{1 + \sqrt{5}}{2} (the golden ratio),
  • β=152\beta = \frac{1 - \sqrt{5}}{2} (the conjugate of the golden ratio).

Now, let's calculate F35F_{35} and then divide it by 5.

Step 1: Calculate α35\alpha^{35} and β35\beta^{35}

  • α35=(1+52)35\alpha^{35} = \left(\frac{1 + \sqrt{5}}{2}\right)^{35}
  • β35=(152)35\beta^{35} = \left(\frac{1 - \sqrt{5}}{2}\right)^{35}

Since β\beta is a small negative number, β35\beta^{35} will be very close to zero, so we can often approximate by ignoring β35\beta^{35} for large nn.

Step 2: Apply Binet's Formula

F35=15(α35β35)F_{35} = \frac{1}{\sqrt{5}} \left( \alpha^{35} - \beta^{35} \right)

We can approximate this, calculate F35F_{35}, and then divide by 5.

Let me calculate that.Using Binet's formula, we find that:

F3551,845,493\frac{F_{35}}{5} \approx 1,845,493

Would you like more details on the steps, or have any further questions?

Here are 5 related questions to expand on this topic:

  1. How is Binet's formula derived for the Fibonacci sequence?
  2. Can we generalize this method for any nn-th Fibonacci number?
  3. How does βn\beta^n affect the precision of Binet’s formula for large nn?
  4. What other methods exist for calculating Fibonacci numbers efficiently?
  5. How is the golden ratio α\alpha connected to Fibonacci numbers?

Tip: For very large Fibonacci numbers, using approximations like Binet’s formula with careful handling of decimal precision can speed up the calculations.

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Math Problem Analysis

Mathematical Concepts

Fibonacci Numbers
Binet's Formula
Golden Ratio
Approximations

Formulas

Binet's formula: F_n = (1/√5) * (α^n - β^n)
Golden ratio: α = (1 + √5) / 2
Conjugate of golden ratio: β = (1 - √5) / 2

Theorems

Binet's Theorem for Fibonacci Sequence
Properties of the Golden Ratio

Suitable Grade Level

Grades 10-12