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Math Help - Lenght and gradient.

  1. #1
    Member helloying's Avatar
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    Jul 2008
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    Lenght and gradient.

    Given the points P(k,3) Q(1,1) and R(6,2), find the possibe values of k if PQ=2QR.

    I did it by finding length of 2QR= 2√(1-6)+(1-2) and i got 2√26
    so PQ=2√26
    √(k-1) +(3-1) = 2√26
    √(k -2k+1+4)=2√26

    how to find the k? the ans is 11 and -9 and i dont know how to get it
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  2. #2
    Super Member
    Joined
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    Quote Originally Posted by helloying View Post
    Given the points P(k,3) Q(1,1) and R(6,2), find the possibe values of k if PQ=2QR.

    I did it by finding length of 2QR= 2√(1-6)+(1-2) and i got 2√26
    so PQ=2√26
    √(k-1) +(3-1) = 2√26
    √(k -2k+1+4)=2√26

    how to find the k? the ans is 11 and -9 and i dont know how to get it
    Stop here: √(k-1) +(3-1) = 2√26
    Square both sides and then move 4 to the other side. Can you solve for k now?
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