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Math Help - #1 Graph ellipse. #2 Subtracting polynomials.

  1. #1
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    Question #1 Graph ellipse. #2 Subtracting polynomials.

    Stuck on two questions that was in a review section.

    1) How can I graph the ellipse: x^2/4 + y^2/36 = 1?




    2) How do I solve for x: 3x/2 - 3/4 = x/8?

    Here's what I've done so far:

    3x(4)/2 - 3(2)/4 = x/8

    12x/2 - 6/4 = x/8

    48x/8 - 12/8 = 4x/32.........this is where I got stuck when trying to get all the denominators the same.


    Thanks in advance.
    Last edited by Mulya66; April 5th 2007 at 07:04 AM. Reason: #2 was x/8 and not 8/x.
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  2. #2
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    Quote Originally Posted by Mulya66 View Post
    2) How do I solve for x: 3x/2 - 3/4 = 8/x?

    Here's what I've done so far:

    3x(4)/2 - 3(2)/4 = x/8

    12x/2 - 6/4 = x/8

    48x/8 - 12/8 = 4x/32.........this is where I got stuck when trying to get all the denominators the same.


    Thanks in advance.
    Hint: Multiply everything by 8x. (See what happens).
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  3. #3
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    Quote Originally Posted by Mulya66 View Post
    Stuck on two questions ...

    3x/2 - 3/4 = 8/x

    12x/2 - 6/4 = x/8
    Hello,

    you unfortunately turned over the fraction...

    Use the TPH's hint...

    EB
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  4. #4
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    Hello, Mulya66!

    Graph the ellipse: .x/4 + y/36 .= .1

    First of all, the ellipse is centered at the origin.

    Recall that the denominators give you the "dimensions" of the ellipse.

    Since a = 4, a = 2.
    . . The ellipse extends 2 units to the left and right of center.

    Since b = 36, b = 6.
    . . The ellipse extends 6 units up and down from the center.



    2) Solve: .3x/2 - 3/4 .= .8/x

    Multiply through by the LCM, 4x

    . . . . 3x . - . .3 . . . . . 8
    . . 4x--- - 4x-- .= .4x-- . . 6x - 3x .= .32
    . . . . .2 . - . .4 . - . - . x

    and solve the quadratic equation.

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  5. #5
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    Quote Originally Posted by Soroban View Post
    Hello, Mulya66!


    First of all, the ellipse is centered at the origin.

    Recall that the denominators give you the "dimensions" of the ellipse.

    Since a = 4, a = 2.
    . . The ellipse extends 2 units to the left and right of center.

    Since b = 36, b = 6.
    . . The ellipse extends 6 units up and down from the center.


    [/size]
    Oh okay, so a^2 is for left and right and b^2 is up and down.

    #2 was actually x/8, sorry. But last night, I got x = 6/11 ~ 0.5455.

    Thanks a lot, everyone. =)
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