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Math Help - [SOLVED] Simple Co-Ordinate Geometry

  1. #1
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    Cool [SOLVED] Simple Co-Ordinate Geometry

    Q#1

    Are the following equations of line same in sense of meaning and values? How are you supposed to arrange your final line's equation?

    2x-3y+9=0 (Answer in the book)

    3y-2x-9=0 (My answer)

    OR

    3y=2x+3

    Q#2

    If the line of equation is

    2x-3y+9=0

    Shouldn't we be able to find out the value of y for it's corresponding value of x? I mean if I am 100% sure that at a certain point, in my question where the above line is intersecting with the y-axis, thus x = 0, right?

    So if I put x=0 in the above equation, my value for the corresponding y comes as 1. But in the answer of the question the examiner has taken the value of y as the y-intercept.

    Please explain what am I doing wrong.

    Thanks in advance!
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  2. #2
    MHF Contributor Amer's Avatar
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    Quote Originally Posted by unstopabl3 View Post
    Q#1

    Are the following equations of line same in sense of meaning and values? How are you supposed to arrange your final line's equation?

    2x-3y+9=0 (Answer in the book)

    3y-2x-9=0 (My answer)

    OR

    3y=2x+3

    Q#2

    If the line of equation is

    2x-3y+9=0

    Shouldn't we be able to find out the value of y for it's corresponding value of x? I mean if I am 100% sure that at a certain point, in my question where the above line is intersecting with the y-axis, thus x = 0, right?

    So if I put x=0 in the above equation, my value for the corresponding y comes as 1. But in the answer of the question the examiner has taken the value of y as the y-intercept.

    Please explain what am I doing wrong.

    Thanks in advance!
    for the first question it is the same in that way , but if we write them as a functions it is different

    f(x,y) = 2x -3y +9 and g(x,y)=3y-2x-9 are different functions

    second question the line intersect with y-axis when x=0 and intersect with x-axis when y=0

    so

    2x-3y+9 =0 intersect y-axis at

    2(0) -3y +9 =0 \Rightarrow y =3 so the line intersect with y-axis at (0,3)

    in the same way you can find where the line intersect with x-axis set y=0 and then find x value
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  3. #3
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    Cool

    Thanks for the quick reply. I feel stupid about Q2 as I made a mistake when I solved it myself

    For the first question, I want to ask is that how are we supposed to arrange our final equation. For example in my question you can see that I have three variations of the equation and all of them are correct but what I mean is what is the most appropriate way of writing our final equation?

    For example if I get the following equation after solving:

    5y=3x+5

    Am I supposed to do this

    5y-3x-5=0

    OR

    -y+3x+5=0

    OR

    5y-3x=0

    OR

    y=(3x+5)/5


    OR

    Leave the equation as it is

    5y=3x+5

    You get my point? How do you know your final equation should look like?

    Thanks!
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  4. #4
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    Quote Originally Posted by unstopabl3 View Post
    Thanks for the quick reply. I feel stupid about Q2 as I made a mistake when I solved it myself

    For the first question, I want to ask is that how are we supposed to arrange our final equation. For example in my question you can see that I have three variations of the equation and all of them are correct but what I mean is what is the most appropriate way of writing our final equation?

    For example if I get the following equation after solving:

    5y=3x+5

    Am I supposed to do this

    5y-3x-5=0

    OR

    -y+3x+5=0

    OR

    5y-3x=0

    OR

    y=(3x+5)/5


    OR

    Leave the equation as it is

    5y=3x+5

    You get my point? How do you know your final equation should look like?

    Thanks!
    Hi

    it depends on the question .. If it asks to be an intercept form , then by all means put it in an intercept forms , and same goes for general form or standard form .

    But if the question did not specify , then you can just put it in any of those forms .
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  5. #5
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    Cool

    Thanks, what would be the standard/general form and the intercept form?

    Thanks!
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  6. #6
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    Quote Originally Posted by unstopabl3 View Post
    Thanks, what would be the standard/general form and the intercept form?

    Thanks!
    3y+2x-4=0 . this would be standard form

    y=-2/3 x + 4/3 , general form .

    In general ,

    Ax+By+C=0 .. standard

    y=mx+c .. general
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  7. #7
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    Thanks
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