Math Problem Statement

x=?

Solution

The equation you provided is a modular arithmetic problem:

117+217+317++4917x (mod 17)1^{17} + 2^{17} + 3^{17} + \dots + 49^{17} \equiv x \ (\text{mod}\ 17)

We are required to find the value of xx in the set Z17\mathbb{Z}_{17} (which means xx is an integer between 0 and 16).

Solution:

  1. Euler's Theorem Application: For any integer aa that is not divisible by 17, a161 (mod 17)a^{16} \equiv 1 \ (\text{mod}\ 17). Thus: a17a (mod 17)a^{17} \equiv a \ (\text{mod}\ 17)

  2. Calculation: Since 1717 is a prime number, the theorem applies to all numbers except multiples of 17. In this sum, none of the integers 1 to 49 are multiples of 17.

    Therefore: 117+217+317++49171+2+3++49 (mod 17)1^{17} + 2^{17} + 3^{17} + \dots + 49^{17} \equiv 1 + 2 + 3 + \dots + 49 \ (\text{mod}\ 17)

  3. Sum of the First 49 Numbers: The sum of the first nn integers is given by: Sum=n(n+1)2\text{Sum} = \frac{n(n+1)}{2} For n=49n = 49: Sum=49×502=1225\text{Sum} = \frac{49 \times 50}{2} = 1225

  4. Modular Reduction: Now, find 1225mod171225 \mod 17. 1225÷1772(quotient),1225(72×17)=12251224=11225 \div 17 \approx 72 \quad \text{(quotient)}, \quad 1225 - (72 \times 17) = 1225 - 1224 = 1 Thus: 12251 (mod 17)1225 \equiv 1 \ (\text{mod}\ 17)

So, x=1x = 1.

Final Answer:

x=1x = 1

Would you like further details or explanations on any step? Here are some questions related to the problem:

  1. What is Euler's theorem, and how is it used in modular arithmetic?
  2. How can we generalize this approach to any prime modulus?
  3. What would the solution be if the problem asked for mod 19 instead of mod 17?
  4. Can you explain the process of summing an arithmetic series in more detail?
  5. How would the problem change if the exponent were different, say 18 instead of 17?

Tip: Modular arithmetic problems often become simpler when using properties like Euler's theorem or Fermat's little theorem.

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Math Problem Analysis

Mathematical Concepts

Modular Arithmetic
Summation of Series
Euler's Theorem

Formulas

Sum of arithmetic series: Sum = n(n+1)/2

Theorems

Euler's Theorem

Suitable Grade Level

Advanced High School