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Thread: Please help w/ 1/x+1 - 2/(x+1)^2 - x^2-1/(x+1)^3

  1. #1
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    Question Please help w/ 1/x+1 - 2/(x+1)^2 - x^2-1/(x+1)^3

    Hi guys, i'm new here, just registered, so I want to greet you all first.

    Could you please help me with solving this expression, the result should be 0, but I can't seem to get read of all the factors..

    Here it is: 1/x+1 - 2/(x+1)^2 - x^2-1/(x+1)^3

    Could you please mention how are you doing the factoring?

    Thanks million.

  2. #2
    Elite Member stapel's Avatar
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    Cool

    Quote Originally Posted by factor View Post
    Could you please help me with solving this expression, the result should be 0, but I can't seem to get read of all the factors..

    Here it is: 1/x+1 - 2/(x+1)^2 - x^2-1/(x+1)^3
    This is an expression, which can be simplified; having no "equals" sign, it is not an equation which can be solved. I'm guessing the instructions specify "simplify"...?[/quote]

    Quote Originally Posted by factor View Post
    Could you please mention how are you doing the factoring?
    I'm not sure what you mean by "doing the factoring" here...? The first step for combining these fractions will be to convert them all to the same common denominator. How far have you gotten in that process?

    When you reply, please show all of your steps so far. Thank you!

  3. #3
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    You are missing required grouping symbols. Before you work on stapel's strategy, this is what you really intended:

    1/(x + 1) - 2/(x + 1)^2 - (x^2 - 1)/(x+1)^3


    That is, [tex] \ \ \dfrac{1}{x + 1} \ - \ \dfrac{2}{(x + 1)^2} \ - \ \dfrac{x^2 - 1}{(x + 1)^3}[/tex].
    Last edited by lookagain; 09-13-2017 at 09:24 AM.

  4. #4
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    Quote Originally Posted by factor View Post
    Hi guys, i'm new here, just registered, so I want to greet you all first.

    Could you please help me with solving this expression, the result should be 0, but I can't seem to get read of all the factors..

    Here it is: 1/x+1 - 2/(x+1)^2 - x^2-1/(x+1)^3

    Could you please mention how are you doing the factoring?

    Thanks million.
    As lookagain has explained, you need to be careful about using grouping symbols.

    Stapel has given you the general method for attacking this kind of problem. For this specific problem, however, there is a short cut. HINT:

    [tex]x^2 - 1 = (x - 1)(x + 1).[/tex]

    By the way, it is not necessarily true that simplifying an algebraic expression will result in a number.

  5. #5
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    Hi, Thank you all for the answers I've got this with your help, thank you.
    I was working on similar expressions that require factoring, and when I came to this automatically started applying the same strategy. Was unable to recognise that it requires different approach. Factoring brought me to a dead end and couldn't continue further, so I was wondering what I'm doing wrong.
    The hint about the common denominator really helped, thanks. And sorry about the symbols previously...I still can't get around them here. I'll be practicing

  6. #6
    Elite Member mmm4444bot's Avatar
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    Quote Originally Posted by factor View Post
    And sorry about the symbols previously...I still can't get around them here.
    What are you thinking, when you say "get around [symbols]"?
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

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