Math Problem Statement

Compute the following expression in 𝔽67. [15] βˆ’ [22] Divided by [8] β‹… [14]

Solution

To solve the expression [15]βˆ’[22][8]β‹…[14]\frac{[15] - [22]}{[8] \cdot [14]} in the finite field F67\mathbb{F}_{67}, we must follow these steps:

  1. Subtraction in F67\mathbb{F}_{67}: [ [15] - [22] \equiv 15 - 22 \equiv -7 \equiv 60 \pmod{67} ] Here, βˆ’7-7 is equivalent to 6060 in F67\mathbb{F}_{67} because adding 67 to -7 gives us 60.

  2. Multiplication in F67\mathbb{F}_{67}: [ [8] \cdot [14] \equiv 8 \times 14 \equiv 112 \pmod{67} ] To find 112mod  67112 \mod 67: 112Γ·67=1remainder: 45112 \div 67 = 1 \quad \text{remainder: } 45 Thus, 112≑45(mod67)112 \equiv 45 \pmod{67}.

  3. Finding the Inverse of [45][45] in F67\mathbb{F}_{67}: To compute the division, we need to find the multiplicative inverse of [45][45] modulo 67. We can use the Extended Euclidean Algorithm to find this inverse.

    Applying the Extended Euclidean Algorithm to 6767 and 4545:

    67=1Γ—45+2267 = 1 \times 45 + 22 45=2Γ—22+145 = 2 \times 22 + 1 22=22Γ—1+022 = 22 \times 1 + 0

    Back-substitution gives us: 1=45βˆ’2Γ—221 = 45 - 2 \times 22 1=45βˆ’2Γ—(67βˆ’1Γ—45)1 = 45 - 2 \times (67 - 1 \times 45) 1=3Γ—45βˆ’2Γ—671 = 3 \times 45 - 2 \times 67

    Therefore, the inverse of 4545 modulo 6767 is 33.

  4. Division in F67\mathbb{F}_{67}: 6045≑60Γ—3(mod67)\frac{60}{45} \equiv 60 \times 3 \pmod{67} 60Γ—3=18060 \times 3 = 180

    To find 180mod  67180 \mod 67: 180Γ·67=2remainder: 46180 \div 67 = 2 \quad \text{remainder: } 46 Thus, 180≑46(mod67)180 \equiv 46 \pmod{67}.

The final result is [46][46] in F67\mathbb{F}_{67}.

If you have any questions or need further details, feel free to ask!

Here are some related questions you might find interesting:

  1. How do you find the inverse of a number in a finite field?
  2. What is the significance of finite fields in cryptography?
  3. How do operations in finite fields differ from those in real numbers?
  4. What are some applications of finite fields in computer science?
  5. Can you explain the process of the Extended Euclidean Algorithm?
  6. How do you perform modular arithmetic efficiently?
  7. What are the properties of finite fields?
  8. How is subtraction defined in a finite field?

Tip: In modular arithmetic, always ensure your results are within the modulus range by adding or subtracting the modulus to adjust negative values or large numbers.

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Math Problem Analysis

Mathematical Concepts

Finite Fields
Modular Arithmetic
Extended Euclidean Algorithm

Formulas

Modular Inverse Calculation

Theorems

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Suitable Grade Level

Advanced Mathematics