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QR, can you do this?

Discussion in 'DAT Discussions' started by Dencology, Nov 29, 2008.

  1. Dencology

    2+ Year Member

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    guys how do you do this q:

    A Find the bisector of a segment that joins (1, 1) and (9, 5).
    A. y + 2x = 13 B. 2y – x = 1 C. y – 2x = -2 D. 2y + x = 11 E. 2y – x = 1ans is A
     
  2. Sublimation

    5+ Year Member

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    First find the slope. Which is delta y over dleta x. gives u 1/2, now the line that bisects it will have a slope that is the negative reciprocal of 1/2 which is -2. the slope of the line segment in question here. Change the answer choices to y=mx+b because its linear and m is your slope. Just solve them in order and ull hit the right one on the first try. Hope that helps.
     
  3. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist 7+ Year Member

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    To do it without subbing in numbers (ie if this was a 'fill in the blank' question) you would need the midpoint of that segment. That's just [ (x1+x2)/2 , (y1+y2)/2 ] = (5, 3).

    With a slope of -2 you get y-3 = -2(x-5) which simplifies to y = -2x +13 which is y + 2x = 13, choice A.
     
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