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Math Help - Solve the inequality 20-3y > y+4

  1. #1
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    Solve the inequality 20-3y > y+4

    I am not sure of my workings but here it is:

    20-3y = y+4
    20-4 = y+3y
    16=4y
    y=4

    Therefore, y>4

    Also, how do I illustrate the answer on a number line? Not quite sure what they are asking for
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  2. #2
    Super Member TheChaz's Avatar
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    Re: Solve the inequality 20-3y > y+4

    Quote Originally Posted by FailInMaths View Post
    I am not sure of my workings but here it is:

    20-3y > y+4
    20-4 > y+3y
    16>4y
    y<4

    ...

    Also, how do I illustrate the answer on a number line? Not quite sure what they are asking for
    The above is how it should read. Why did you switch to "=" ?
    To graph y < 4
    Mark "4" on a number line. Either circle it, or put a " ) " right parenthesis there, and then shade/draw a line to the left (where "lesser" numbrs are)
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  3. #3
    MHF Contributor FernandoRevilla's Avatar
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    Re: Solve the inequality 20-3y > y+4

    20-3y>y+4\Leftrightarrow 16>4y \Leftrightarrow 4>y so the solutions are the elements of (-\infty,4) .


    Edited: Sorry, I didn't see TheChaz's post.
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  4. #4
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    Re: Solve the inequality 20-3y > y+4

    Quote Originally Posted by TheChaz View Post
    The above is how it should read. Why did you switch to "=" ?
    To graph y < 4
    Mark "4" on a number line. Either circle it, or put a " ) " right parenthesis there, and then shade/draw a line to the left (where "lesser" numbrs are)
    Oh, I get it now, thanks!
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  5. #5
    Super Member TheChaz's Avatar
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    Re: Solve the inequality 20-3y > y+4

    Quote Originally Posted by FernandoRevilla View Post
    20-3y>y+4\Leftrightarrow 16>4y \Leftrightarrow 4>y so the solutions are the elements of (-\infty,4) .


    Edited: Sorry, I didn't see TheChaz's post.
    No need for apologies, especially since you included the solution in interval notiation!
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