Math Problem Statement

Consider the number M = 7^2 x 23 x 31, where 7, 23, and 31 are prime numbers. List all of the factors of M without computing the value of M first. Clearly show or explain how you were able to find all of the factors.

Solution

The number M=72×23×31M = 7^2 \times 23 \times 31 consists of the prime factorization of MM, where the prime numbers are 7, 23, and 31, and 7 is raised to the power of 2. Let's find all the factors of MM by using the prime factorization directly without computing the product.

Steps to find all factors:

  1. Prime factorization: The prime factorization of MM is 72×231×3117^2 \times 23^1 \times 31^1.

  2. Number of factors: The total number of factors of a number is determined by adding 1 to each of the exponents in its prime factorization and multiplying these results.

    • For 727^2, there are 2+1=32 + 1 = 3 possible factors: 70,71,727^0, 7^1, 7^2.
    • For 23123^1, there are 1+1=21 + 1 = 2 possible factors: 230,23123^0, 23^1.
    • For 31131^1, there are 1+1=21 + 1 = 2 possible factors: 310,31131^0, 31^1.

    So, the total number of factors is: 3×2×2=123 \times 2 \times 2 = 12 There are 12 factors in total.

  3. Generating factors: To find all the factors, we take all combinations of powers of 7, 23, and 31:

    • Factors of the form 7a×23b×31c7^a \times 23^b \times 31^c, where a=0,1,2a = 0, 1, 2, b=0,1b = 0, 1, and c=0,1c = 0, 1.

    Here are all the possible combinations:

    • a=0,b=0,c=0a = 0, b = 0, c = 0: 70×230×310=17^0 \times 23^0 \times 31^0 = 1
    • a=1,b=0,c=0a = 1, b = 0, c = 0: 71×230×310=77^1 \times 23^0 \times 31^0 = 7
    • a=2,b=0,c=0a = 2, b = 0, c = 0: 72×230×310=497^2 \times 23^0 \times 31^0 = 49
    • a=0,b=1,c=0a = 0, b = 1, c = 0: 70×231×310=237^0 \times 23^1 \times 31^0 = 23
    • a=1,b=1,c=0a = 1, b = 1, c = 0: 71×231×310=7×23=1617^1 \times 23^1 \times 31^0 = 7 \times 23 = 161
    • a=2,b=1,c=0a = 2, b = 1, c = 0: 72×231×310=49×23=11277^2 \times 23^1 \times 31^0 = 49 \times 23 = 1127
    • a=0,b=0,c=1a = 0, b = 0, c = 1: 70×230×311=317^0 \times 23^0 \times 31^1 = 31
    • a=1,b=0,c=1a = 1, b = 0, c = 1: 71×230×311=7×31=2177^1 \times 23^0 \times 31^1 = 7 \times 31 = 217
    • a=2,b=0,c=1a = 2, b = 0, c = 1: 72×230×311=49×31=15197^2 \times 23^0 \times 31^1 = 49 \times 31 = 1519
    • a=0,b=1,c=1a = 0, b = 1, c = 1: 70×231×311=23×31=7137^0 \times 23^1 \times 31^1 = 23 \times 31 = 713
    • a=1,b=1,c=1a = 1, b = 1, c = 1: 71×231×311=7×23×31=49737^1 \times 23^1 \times 31^1 = 7 \times 23 \times 31 = 4973
    • a=2,b=1,c=1a = 2, b = 1, c = 1: 72×231×311=49×23×31=346937^2 \times 23^1 \times 31^1 = 49 \times 23 \times 31 = 34693

List of all factors:

1,7,23,31,49,161,217,713,1127,1519,4973,346931, 7, 23, 31, 49, 161, 217, 713, 1127, 1519, 4973, 34693

These are all the factors of MM, found by systematically combining the powers of the primes.

Would you like more details on how these combinations were formed, or do you have any other questions?


Here are 5 related questions to deepen understanding:

  1. How do you compute the number of divisors from a prime factorization?
  2. What is the difference between finding prime factors and finding all factors of a number?
  3. Can you explain how to find the greatest common divisor using prime factorization?
  4. How would the process change if 77, 2323, and 3131 were not prime numbers?
  5. What are the applications of factorization in number theory or algebra?

Tip: For large numbers, prime factorization makes finding divisors and solving equations much easier.

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Math Problem Analysis

Mathematical Concepts

Prime Factorization
Factors
Combinatorics

Formulas

Number of factors = (exponent of prime factor 1 + 1) x (exponent of prime factor 2 + 1) x ...

Theorems

Fundamental Theorem of Arithmetic

Suitable Grade Level

Grades 9-12