Results 1 to 4 of 4

Math Help - Perpendicular Line EQ: x-2y-3=0

  1. #1
    Junior Member
    Joined
    Jun 2010
    Posts
    50

    Perpendicular Line EQ: x-2y-3=0

    I whipped through these in relatively short order until this one

    Passing through (4,-7) and perpendicular to the line whose equation is  x -2y -3=0

    x -2y -3 = 0 : Subtract x from both sides and add 3 to both sides so that

    -2y = -x +3 : Divide -x by -2 to get


    \frac{\1}{2}x The negative reciprocal of 1/2 is -2 so...


    y- (-7)= -2(x-4) to get

    y +7 = -2x +8 : subtract both 7 and y to get

    -2x -y +1 = 0 : The answer in the book is the complete opposite. It gives

    2x +y -1 = 0

    But to get that requires something that I'm missing. Either that or the book is wrong. The latter is very rare and the former much more likely. Any and all help is appreciated. Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Jul 2011
    Posts
    61

    Re: Perpendicular Line EQ: x-2y-3=0

    Your answer is in standard form of a line which shouldn't have a Negative x so all you do is multiply by -1. Which gives the same answer.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor Siron's Avatar
    Joined
    Jul 2011
    From
    Norway
    Posts
    1,250
    Thanks
    20

    Re: Perpendicular Line EQ: x-2y-3=0

    It's both correct, because if you multiply both sides of your equation with -1 you get the answer in the book.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Jun 2010
    Posts
    50

    Re: Perpendicular Line EQ: x-2y-3=0

    Cool. Thanks guys.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Perpendicular line.
    Posted in the Algebra Forum
    Replies: 1
    Last Post: October 4th 2011, 07:26 PM
  2. Replies: 4
    Last Post: September 24th 2011, 07:53 PM
  3. Replies: 4
    Last Post: May 12th 2011, 01:18 PM
  4. Finding a line perpendicular to another line
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: December 12th 2009, 10:13 PM
  5. equation of a line perpendicular to the line defined
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: June 6th 2007, 10:02 AM

Search Tags


/mathhelpforum @mathhelpforum