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Anyone Help me with Maths?

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  • 15-11-2009 2:08pm
    #1
    Les_Rebels123
    Registered Users Posts: 52 ✭✭


    here's the question:
    express L: 4x-y+2+k(3x-3y+7)=0 in the form ax+by+c=0.
    Hence find the value of k if the slope of L is 2.

    So far ive got:
    4x+3kx-y-3ky+2+7k=0 , and now I'm Stuck :(:(

    Have i gone about it the wrong way?

    Any help would be greatly appreciated! :):D

    thanks
    Les_Rebels123


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    #2
    NU8
    Registered Users Posts: 235 ✭✭NU8


    Factorise and get:
    X(4+3k) - Y(1+3k) + 2k+7 = 0

    Remember: Y = mX + c

    Y(1+3k) = X(4+3k) + 2k+7
    Y= X(4+3k/1+3k) + (2k+7/1+3k)
    Therefore M = (4+3k/1+3k) = 2
    2+6k = 4 + 3k
    3k = 2
    k = 2/3

    I think that's it, hopefully someone will correct me if I'm wrong.


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    #3
    caroline1111
    Registered Users Posts: 224 ✭✭caroline1111


    4x-y+2+k(3x-3y+7)=0
    4x-y+2+3xk-3yk+7k
    x(4+3k)+y(-1-3k)+2+7k=0
    y(-1-3k)=(-4-3k)x-2-7k
    y=-4-3k
    -1-3k
    =4+3k =2
    1+3k
    4+3k=2+6k
    -3k=-2
    k= 2/3


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    #4
    Keen2win
    Registered Users Posts: 153 ✭✭Keen2win


    Oh jesus, that looks hard!

    I think I'l drop down:D


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    #5
    NU8
    Registered Users Posts: 235 ✭✭NU8


    caroline1111 wrote: »
    4x-y+2+k(3x-3y+7)=0
    4x-y+2+3xk-3yk+7k
    x(4+3k)+y(-1-3k)+2+7k=0
    y(-1-3k)=(-4-3k)x-2-7k
    y=-4-3k
    -1-3k
    =4+3k =2
    1+3k
    4+3k=2+6k
    -3k=-2
    k= 2/3

    That's exactly what I wrote :confused:
    but since we both got the same answer I'm assuming that it is the correct one.


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