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Thread: Factorize x^5-16x- how do u do questions like this?

  1. #1

    Factorize x^5-16x- how do u do questions like this?

    Hi, I wanted to ask how to do questions like the one that I put in the title,\-

    Factorize x^5-16x- how do u do questions like this?

    would you o, in the first step, separate the equation into x^2.5 power,? no, right? I'm not sure- that's the only way that i can see right now,... can u help?

    Also, do u know about the cross method for factorization? I don't get how that works either. Please help. Thank you!

    ~shapoey
    Last edited by stapel; 02-27-2018 at 06:33 PM.

  2. #2
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    Quote Originally Posted by shapoey View Post
    Hi, I wanted to ask how to do questions like the one that I put in the title,\- would you o, in the first step, separate the equation into x^2.5 power,? no, right? I'm not sure- that's the only way that i can see right now,... can u help?

    Also, do u know about the cross method for factorization? I don't get how that works either. Please help. Thank you!


    ~shapoey
    x^5 - 16x ....................... Is there a common factor ← yes → factor that out.

    = x * (x^4 - 16)

    = x * (x^4 - 2^4)

    What is special about the expression within the parentheses?
    “... mathematics is only the art of saying the same thing in different words” - B. Russell

  3. #3
    Elite Member stapel's Avatar
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    Cool

    Quote Originally Posted by shapoey View Post
    Hi, I wanted to ask how to do questions like the one that I put in the title,\-

    Factorize x^5-16x- how do u do questions like this?
    To learn how to do simple factorization, try here. This will explain the first step in the response you received earlier.

    To learn how to do special factorization (of the difference-of-squares type suggested in the previous response), try here.

    To learn how to factor quadratics (a topic which usually occurs between the two topics above), try here.

    Quote Originally Posted by shapoey View Post
    would you o, in the first step, separate the equation into x^2.5 power,?
    I'm sorry, but I don't know what this means...? How are you getting a power of 5/2? Where are the radicals coming from? How did you go from "x^5 - 16x" to... whatever it was that you got? What did you get?

    Quote Originally Posted by shapoey View Post
    Also, do u know about the cross method for factorization? I don't get how that works either.
    Please provide an example what this "cross method". Thank you!

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    Quote Originally Posted by stapel View Post
    Please provide an example what this "cross method". Thank you!
    I shall bet you my next martini that what is meant is the difference of squares.

    And of course you can use difference of squares in this problem.

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    Elite Member stapel's Avatar
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    Cool

    Quote Originally Posted by JeffM View Post
    I shall bet you my next martini that what is meant is the difference of squares.

    And of course you can use difference of squares in this problem.
    After doing the initial simple factorization, yes!

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