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Solution Check - Graphing Linear Function watch

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    Hey again,
    many of you have been pretty cool by checking some of my answers so far and helping me out with questions... maths isnt my strong point (yet ). just want to say thanks 4 that....

    anyway been given the equation 2x + 4y = -8

    a) write y as function of x and find intercept/root.

    ANSWER:

    2x + 4y = - 8
    4y = -2x - 8
    y = -1/2x - 2

    f(x) = -1/2x - 2 .... intercept = -2

    root = -2/-1/2 = 4

    b) draw graph..

    c) slope of function

    ANSWER:

    slope = v/h

    = 0 - 4 / -2 - 0
    = -4/-2
    = 2

    is this correct??
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    (Original post by gavo)
    anyway been given the equation 2x + 4y = -8

    a) write y as function of x and find intercept/root.

    ANSWER:

    2x + 4y = - 8
    4y = -2x - 8
    y = -1/2x - 2

    f(x) = -1/2x - 2 .... intercept = -2

    root = -2/-1/2 = 4

    b) draw graph..

    c) slope of function

    ANSWER:

    slope = v/h

    = 0 - 4 / -2 - 0
    = -4/-2
    = 2

    is this correct??
    No, it's not.
    Hic, find the root, f(x) = 0
    -0.5x - 2 = 0
    x = 2/(-0.5) = -4
    So root = -4?

    But you changed your function 2x + 4y = 8 to y = -2x - 8, you already got the slope of this function = -2. (the coefficient of x)
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    The slope of the graph is going to be the value m, where y = mx + c. So in your case m is -1/2.
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    (Original post by BCHL85)
    No, it's not.
    Hic, find the root, f(x) = 0
    -0.5x - 2 = 0
    x = 2/(-0.5) = -4
    So root = -4?
    sorry silly error on that part

    (Original post by BCHL85)
    But you changed your function 2x + 4y = 8 to y = -2x - 8, you already got the slope of this function = -2. (the coefficient of x)
    i changed function to make it subject of x???
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    (Original post by AntiMagicMan)
    The slope of the graph is going to be the value m, where y = mx + c. So in your case m is -1/2.
    I had a mistake when i typed. He changed from 2x + 4y = - 8 to y = -1/2x - 2
    So the slope is the coefficient of x = -1/2
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    (Original post by BCHL85)
    I had a mistake when i typed. He changed from 2x + 4y = - 8 to y = -1/2x - 2
    So the slope is the coefficient of x = -1/2
    can someone explain whether i was actually meant to change the forumula given the context of the question? (i.e write y as function of x and find intercept/root.)

    NO offence BCHL85 but im not finding your posts of any help, if you would be a bit clearer it would be helpful, we arent all maths genious
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    Yes, the question was asking you to write the equation in the form y = f(x). You did that and then could read off the intercept m when in the form y = mx + c. The 'root' is simply the value of x when y = 0 so the solution to the equation 0 = mx + c i.e. x = -c/m.
    • Thread Starter
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    hi guys,
    understand it all now, thanks for the assistance.

    gav
 
 
 
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