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Math Help - [SOLVED] Algebra homework - please check if these are right ->

  1. #1
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    Question [SOLVED] Algebra homework - please check if these are right ->

    I'm working on my second homework, as I've mentionned before this is a math class I'm taking to get myself up to college math. I'm starting my master's in Human Ress, but I haven't done math since high school, about 20 years ago. My brain just doesn't work as good as it used too?

    If someone would just check if those 3 answers are correct, that would be of great help.

    If:
    P1= 12x^2-6xy+9y^2
    P2= -2x^2+3xy-4y^2
    P3= 2x-y^2

    And:
    M1= -3xy

    1) P3-P2

    =(2x-y^2)-(-2x^2+3xy-4y^2)
    =(2x-y^2)+(2x^2-3xy+4y^2)
    =2x+(-y^2+4y^2)+2x^2-3xy
    =2x+3y^2+2x^2-3xy

    2) P2XP3

    =(-2x^2+3xy-4y^2) (2x-y^2)
    =(-2x^2)x2x+(-2x^2)x(-y^2)+3xyx2x+3xyx(-y^2)+(-4y^2)x2x+(-4y^2)x(-y^2)
    =(-4x^3)+2x^2y^2+6x^2y-3xy^3-8xy^2+4y^4

    3)P1/M1

    =12x^2-6xy+9y^2
    ----------------
    -3xy
    =12x^2 -6xy 9y^2
    ------ + ----- + ------
    -3xy -3xy -3xy

    =-4xy^-2+0.5+-3x^-1y
    =-4xy^-2-x^-1y+0.5
    =-7x^-1y^-1+0.5
    =0.5
    ----
    7xy

    Those are the first three, I'm trying my best not to check everything with you guys because the homework is extensive and I've already had to ask for a prolongation, which cost me 60$ more (on top of the 350$+ they charged for the class), so believe me when I say that this is important for me and you guys are not wasting your time helping me out.

    Thank you so much

    Neenoon
    Last edited by Neenoon; August 13th 2008 at 07:54 AM.
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  2. #2
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    First two are correct. I'm not sure what you wrote in the last one, but here it is anyways:

    \frac{12x^2 - 6xy + 9y^2}{-3xy}

    = \frac{-12x^2 + 6xy - 9y^2}{3xy}

    = \frac{-12x^2}{3xy} + \frac{6xy}{3xy} - \frac{9y^2}{3xy}

    = -\frac{4x}{y} + 2 - \frac{3y}{x}

    = -4xy^{-1} + 2 - 3yx^{-1}

    P.S. You brain works just as good as before, if not better.
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  3. #3
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    Quote Originally Posted by Neenoon View Post

    If:
    P1= 12x^2-6xy+9y^2
    P2= -2x^2+3xy-4y^2
    P3= 2x-y^2

    And:
    M1= -3xy

    1) P3-P2

    =(2x-y^2)-(-2x^2+3xy-4y^2)
    =(2x-y^2)+(2x^2-3xy+4y^2)
    =2x+(-y^2+4y^2)+2x^2-3xy
    =2x+3y^2+2x^2-3xy
    This is correct.

    Quote Originally Posted by Neenoon View Post
    2) P2XP3

    =(-2x^2+3xy-4y^2) (2x-y^2)
    =(-2x^2)x2x+(-2x^2)x(-y^2)+3xyx2x+3xyx(-y^2)+(-4y^2)x2x+(-4y^2)x(-y^2)
    =(-4x^3)+2x^2y^2+6x^2y-3xy^3-8xy^2+4y^4
    This is correct too.

    Quote Originally Posted by Neenoon View Post
    3)P1/M1

    =12x^2-6xy+9y^2
    ----------------
    -3xy
    =12x^2 -6xy 9y^2
    ------ + ----- + ------
    -3xy -3xy -3xy

    =-4xy^-2+0.5+-3x^-1y
    =-4xy^-2-x^-1y+0.5
    =-7x^-1y^-1+0.5
    =0.5
    ----
    7xy
    Here I got:

    -4xy^{-1} + 2 -3x^{-1}y
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  4. #4
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    Thumbs up

    Thank you so much, I was a bit off on that last one. I think I get it now (oh, and I'll trying doing whatever you are doing to post the equation so that they are more readable).
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