Results 1 to 6 of 6

Math Help - line

  1. #1
    Senior Member furor celtica's Avatar
    Joined
    May 2009
    Posts
    271

    line

    considering an equation ax + by + c =0, im supposed to give examples of a, b, c for which the equation does not represent a straight line
    cant find any
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member nikhil's Avatar
    Joined
    Jun 2008
    Posts
    286

    Talking

    a=0
    or
    b=0
    (c any rational number <>0)
    by this you will only get a point but no line
    if a=b=c=0
    even this will not represent a st. line
    Last edited by nikhil; January 12th 2010 at 09:05 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member furor celtica's Avatar
    Joined
    May 2009
    Posts
    271
    if a=0 then the equation becomes by+c=0
    by=-c
    this is a horizontal line, but a line nevertheless, am i right?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member nikhil's Avatar
    Joined
    Jun 2008
    Posts
    286
    yes ur right !
    my bad
    (y=k is a st line parallel to x axis)
    but a=0,b=0,c=0
    will not be a st.line for sure
    see
    0x+0y+0=0
    this will be satisfied by all the points in the plane
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Senior Member furor celtica's Avatar
    Joined
    May 2009
    Posts
    271
    any other situations which would fit the condition? such as other combinations of the parameters equalling zero?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Senior Member nikhil's Avatar
    Joined
    Jun 2008
    Posts
    286

    my thinking

    ax+by+c=0
    then
    a=-(by+c)/x
    now if y,c,b,x are rational numbers then a will also be a rational number (case of 0 has already been discussed)
    so i don't think there is any value of a,b,c (except a=b=c=0) for which equation ax+by+c=0 do not represents a line.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: November 4th 2011, 06:42 PM
  2. Replies: 1
    Last Post: March 18th 2011, 10:36 AM
  3. Replies: 5
    Last Post: November 4th 2009, 06:49 PM
  4. Replies: 0
    Last Post: October 22nd 2009, 11:04 AM
  5. Replies: 4
    Last Post: March 17th 2008, 01:53 PM

Search Tags


/mathhelpforum @mathhelpforum