Math Problem Statement

Find the multiplicative inverse of 32 modulo 97.

Solution

To find the multiplicative inverse of 32mod9732 \mod 97, we need to find an integer xx such that:

32x1mod9732x \equiv 1 \mod 97

This can be done using the Extended Euclidean Algorithm, which helps solve equations of the form ax+by=gcd(a,b)ax + by = \gcd(a, b).

Since 32 and 97 are coprime (gcd(32,97)=1\gcd(32, 97) = 1), there exists an inverse. Here's the process:

  1. Apply the Euclidean algorithm to find the greatest common divisor (gcd) of 32 and 97:

    97=3×32+197 = 3 \times 32 + 1 32=32×1+032 = 32 \times 1 + 0

    So, the gcd is 11, confirming that an inverse exists.

  2. Now, reverse the steps to express 11 as a linear combination of 9797 and 3232:

    From 97=3×32+197 = 3 \times 32 + 1, we can rearrange to: 1=973×321 = 97 - 3 \times 32

  3. Thus, x=3x = -3 is the solution, but we need the inverse to be positive and in the range 0x<970 \leq x < 97. To do this, add 97 to 3-3:

    x=3+97=94x = -3 + 97 = 94

Therefore, the multiplicative inverse of 32mod9732 \mod 97 is 94\boxed{94}.


Would you like more details on how the Extended Euclidean Algorithm works, or do you have any other questions?

Here are 5 related questions for further exploration:

  1. What is the Euclidean Algorithm, and how is it used in finding gcd?
  2. How does the Extended Euclidean Algorithm differ from the standard Euclidean Algorithm?
  3. What is the importance of the multiplicative inverse in modular arithmetic?
  4. Can all numbers have multiplicative inverses modulo nn?
  5. How would the process differ if the modulus was a composite number?

Tip: When finding an inverse, always ensure the number and modulus are coprime (gcd = 1), otherwise, an inverse does not exist.

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Math Problem Analysis

Mathematical Concepts

Modular Arithmetic
Number Theory

Formulas

32x ≡ 1 mod 97
ax + by = gcd(a, b)

Theorems

Extended Euclidean Algorithm
Greatest Common Divisor (GCD)

Suitable Grade Level

Grades 10-12