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Math Help - factoring

  1. #1
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    factoring

    I was just working on some Alg. problems when I was faced with this lil cute problem;

    Factor out:

    r^4-4096

    Well after abusing the calculator I came to dropping the question till I was done with everything and was then given the answer.

    (r^2+64)(r+8)(r-8)



    Well I do hope all of you had a great Xmas and PLEASE have a berry safe New Years!!

    See ya'll later!!!!
    Last edited by ThePerfectHacker; December 29th 2007 at 06:32 PM.
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  2. #2
    Senior Member DivideBy0's Avatar
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    Quote Originally Posted by Morzilla View Post
    I was just working on some Alg. problems when I was faced with this lil cute problem;

    Factor out:

    r^4-4096

    Well after abusing the calculator I came to dropping the question till I was done with everything and was then given the answer.

    (r^2+64)(r+8)(r-8)



    Well I do hope all of you had a great Xmas and PLEASE have a berry safe New Years!!

    See ya'll later!!!!
    Hi Morzilla, this is a difference of perfect squares problem.

    a^2 - b^2 = (a+b)(a-b)

    For this problem, we have

    r^4 - 4096= (r^2)^2 - (64)^2 = (r^2+64)(r^2-64)

    Then the second pair of brackets can be further factored:

    (r^2+64)(r^2-64) = (r^2+64)(r^2-(8)^2) = (r^2+64)(r+8)(r-8)
    Last edited by ThePerfectHacker; December 29th 2007 at 06:32 PM.
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  3. #3
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    yes your right, I never knew that 64^2 was 4096, I would have never guessed and if I did it would have been way too late!!!


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  4. #4
    Senior Member DivideBy0's Avatar
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    Quote Originally Posted by Morzilla View Post
    yes your right, I never knew that 64^2 was 4096, I would have never guessed and if I did it would have been way too late!!!


    Yeah, I would start with a guess... say 60^2, which I know is close, then eventually get more accurate..
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