-c5.LCM and Prime Factorization of A,B,C

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Discussion Overview

The discussion revolves around calculating the least common multiple (LCM) of three numbers A, B, and C, as well as their prime factorization. Participants explore the definitions and properties of LCM and prime factorization, and engage in clarifying the steps involved in the calculation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Post 1 suggests starting with the product of A, B, and C to find the LCM, but does not clarify that this approach is incorrect if the numbers share common factors.
  • Post 2 argues against the initial approach, explaining that the LCM must account for the highest powers of prime factors present in A, B, and C, and provides a detailed breakdown of the factors contributing to the LCM.
  • Post 3 acknowledges a potential error in the definition of B, indicating that this may affect the calculation of the LCM.
  • Post 4 reiterates the principles for calculating the greatest common factor and the least common multiple, emphasizing the use of prime factors raised to their respective highest or lowest powers.

Areas of Agreement / Disagreement

Participants do not reach consensus on the initial method proposed for calculating the LCM. There is disagreement regarding the correct interpretation of the numbers involved, particularly in Post 3, where a correction is noted. The discussion remains unresolved as participants explore different approaches and clarify definitions.

Contextual Notes

There are unresolved issues regarding the correct definition of B, which may impact the calculations. The discussion also highlights the need for clarity in the definitions and properties of LCM and prime factorization.

karush
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Build the least common multiple of A, B, and C
Then write the prime factorization of the least common multiple of A, B, and C.
$A = 2 \cdot 3^2 \cdot 7 \cdot 13 \cdot 23^8$
$B = 2 3^5 \cdot 5^9 \cdot 13$
$C = 2 \cdot 5 \cdot 11^8 \cdot 13^3$
$\boxed{?}$

ok this only has a single answer

definition: Prime factorization is a way of expressing a number as a product of its prime factors.
A prime number is a number that has exactly two factors, 1 and the number itself.


so is our first step $A\cdot B \cdot C$
 
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No, of course not. ABC would be a "common multiple" of A, B, and C but the "LEAST common multiple" only if all three numbers are relatively prime which is not the case here. I see that A and C have a factor of 2 so the LCM will have a factor of 2. A has a factor of [math]3^2[/math] so the LCM will have [math]3^2[/math] as factor. B has a factor of [math]5^9[/math] and C has a factor of 5 so the LCM will have [math]5^9[/math] as a factor. B has 7 as a factor so the LCM has 7 as a factor. C has a factor of 11 so the LCM will have 11 as a factor. A and B have 13 as a factor and C has [math]13^3[/math] as a factor so the LCM will have [math]13^3[/math] as a factor. A has [math]23^8[/math] as a factor and [math]23^5[/math] so the LCM has [math]23^8[/math] as a factor.

The least common multiple of A, B, and C is [math]2(3^2)(5^9)(7)(11)(13^3)(23^8)[/math].
 
sorry I just noticed that $B=2\cdot 3^5\cdot 5^9 \cdot 13$
probably will change every thing
I should just OP the screenshots

Screenshot 2021-12-10 12.52.01 PM.png
 
You still use the same principal:
for the greatest common factor of a set of numbers, take the product of all primes to the smallest power in the given set and for the least common multiple take the product of all primes to the highest power.
 

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