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Homework Help: Finding the x-intercept

  1. Mar 11, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the x-intercept of the line that passes through the point (1; 2) and perpendicular to the
    line joining (1; 1) and (3; 4):



    3. The attempt at a solution

    I want to confirm my steps if it's right ,,,,

    M=(4-1)/(3-1)= 3/2

    y-1=3/2(x-1) ====> y=(3/2)x-1/2

    perpendicular = m1xm2=-1 ====> m2=-2/3

    y-2=-2/3(x-1) ====> y=(-2/3)x+4/5


    making it one equation

    (3/2)x-(1/2)=(2/3)x+(4/3)
    x=11/13
     
  2. jcsd
  3. Mar 11, 2010 #2
    I am not sure what you did here. I am assuming you were trying to combine the equation of the first line with the second line. If so, you have calculated the point of intersection of the two lines, which is not what the question has asked for. The question asked you for the x-intercept of the line.
     
  4. Mar 11, 2010 #3
    aha ,,,
    so I should not combine them ,,,

    (-2/3)x+4/5 = 0 ?

    and the answer will be (10/13,0)
     
  5. Mar 11, 2010 #4
    Looks good to me!
     
  6. Mar 11, 2010 #5
    ops ,,,
    I had a mistake in y=(-2/3)x+4/5 ,,, should be y=(-2/3)x+8/3

    the answer is (4,0) ,,,

    btw the for your helping
     
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