How to Simplify Factorization?

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    Factorization
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Discussion Overview

The discussion revolves around the factorization of the polynomial expression x^3 − 2x^2 − 4x + 8. Participants explore the steps involved in the factorization process and clarify specific points of confusion related to the omission of terms during the grouping of factors.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant presents a factorization of the polynomial and questions why one of the (x - 2) factors appears to be omitted in the final expression.
  • Another participant explains that (x^2 - 4) can be factored as (x - 2)(x + 2), suggesting that one of the (x - 2) factors is included within this expression.
  • A different participant offers a method for understanding the transition from x^2(x − 2) − 4(x − 2) to (x^2 − 4)(x − 2), using a general algebraic identity ab - cb = b(a - c) to illustrate the factorization process.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the factorization steps, with some seeking clarification while others attempt to explain the reasoning behind the factorization. The discussion does not reach a consensus on the clarity of the steps involved.

Contextual Notes

There are indications of confusion regarding the notation used (e.g., the meaning of "^") and the algebraic manipulation steps, which may depend on participants' familiarity with factorization techniques.

Who May Find This Useful

This discussion may be useful for students learning polynomial factorization, particularly those encountering challenges with grouping and recognizing hidden factors in algebraic expressions.

alpha01
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Factorize:
x^3 − 2x^2 − 4x + 8 correct answer:

(x^3 − 2x^2) − (4x − 8)

x^2(x − 2) − 4(x − 2)

(x^2 − 4)(x − 2)

(x − 2)(x + 2)(x − 2)

(x − 2) 2(x + 2)

In the third line where the terms are grouped i don't understand why one of the (x - 2) is omitted? i.e shouldn't it be (x -2)^2 ?
 
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Sorry just realized this should be under the "homework" section. Will post homework questions there in future (in the meantime could a mod please move it there)..
 
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can anyone help please? Its too critical and basic to go any further in the course notes until i understand this
 
... What is ^?
 
alpha01 said:
can anyone help please? Its too critical and basic to go any further in the course notes until i understand this

(x^2 - 4) = (x - 2)(x + 2), so one of the (x - 2) factors was "hiding inside" the (x^2 - 4).
 
Going from:x^2(x − 2) − 4(x − 2)
to:(x^2 − 4)(x − 2)
is your problem? Well consider this:
ab - cb = b(a - c)
Do you agree? If we multiply out on the right we get the left-hand side. Now in your example, a = x^2, b=(x-2), c=4.
Do you see how it works now?
 
qspeechc said:
Going from:x^2(x − 2) − 4(x − 2)
to:(x^2 − 4)(x − 2)
is your problem? Well consider this:
ab - cb = b(a - c)
Do you agree? If we multiply out on the right we get the left-hand side. Now in your example, a = x^2, b=(x-2), c=4.
Do you see how it works now?



thank you
 

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