Results 1 to 4 of 4

Math Help - Help!!!! Slope-Intercept Form

  1. #1
    Junior Member alwaysalillost's Avatar
    Joined
    Apr 2007
    From
    Where my house is.
    Posts
    61

    Help!!!! Slope-Intercept Form

    1. Find the slope and y-intercept of 5x - 2y = 3.

    2. Indicate which of the following sets of lines are parallel, perpendicular, or neither. Show your work.
    (a) y = 2x - 5
    y = 2x + 5

    (b) 3x + y = 5
    -x + 3x = 6

    (c) 3x + y =5
    x + y = 3


    I really need help! Please explain to me how to find the answers to these problems. Thanks for any help you can give me!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by alwaysalillost View Post
    1. Find the slope and y-intercept of 5x - 2y = 3.
    when the equation of a line is written in the form, y = mx + b, m is the slope, and b is the y-intercept. so we have,

    5x - 2y = 3
    => 2y = 5x - 3
    => y = (5/2)x - 3/2

    so the slope is 5/2 and the y-intercept is -3/2



    2. Indicate which of the following sets of lines are parallel, perpendicular, or neither. Show your work.
    (a) y = 2x - 5
    y = 2x + 5
    two lines are parallel if they have the same slope (or gradient)
    two lines are perpendicular if there slopes are negative inverses of each other. that is, if two lines are perpendicular and the slope of one is m, then the slope of the other is -1/m. example. if the slope of a line is 2, then the slope of the line perpendicular to it is -1/2

    so we have,
    y = 2x - 5
    y = 2x + 5

    these lines are parallel, since both have a slope of 2, there is no work to show

    (b) 3x + y = 5
    -x + 3x = 6
    the first line is:
    3x + y = 5
    => y = -3x + 5 ----------> slope = -3

    the second line is:
    hold on, you have two x's here, which should be the y?

    (c) 3x + y =5
    x + y = 3
    the first line is:
    3x + y = 5
    => y = -3x + 5 ------------> slope = -3

    the second line is:
    x + y = 3
    => y = -x + 3 -------------> slope = -1

    since -3 not= -1
    and -3 not= 1/1
    the lines are neither perpendicular nor parallel
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member alwaysalillost's Avatar
    Joined
    Apr 2007
    From
    Where my house is.
    Posts
    61
    Quote Originally Posted by Jhevon View Post
    the first line is:
    3x + y = 5
    => y = -3x + 5 ----------> slope = -3

    the second line is:
    hold on, you have two x's here, which should be the y?
    Sorry about that...you are right. I wrote it wrong.

    3x + y = 5
    -x + 3y = 6

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by alwaysalillost View Post
    Sorry about that...you are right. I wrote it wrong.

    3x + y = 5
    -x + 3y = 6
    3x + y = 5
    -x + 3y = 6

    the first line is:
    3x + y = 5
    => y = -3x + 5 ----------> slope = -3

    the second line is:
    -x + 3y = 6
    => 3y = x + 6
    => y = (1/3)x + 2 -------> slope = 1/3

    since the slopes are negative inverses of each other, the two lines are perpendicular
    Last edited by Jhevon; May 8th 2007 at 03:35 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: February 3rd 2011, 06:41 PM
  2. Slope intercept form
    Posted in the Pre-Calculus Forum
    Replies: 6
    Last Post: January 3rd 2011, 11:41 AM
  3. Standard form/Slope-intercept form
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 9th 2009, 08:04 PM
  4. Slope Intercept Form
    Posted in the Algebra Forum
    Replies: 4
    Last Post: January 10th 2008, 10:51 PM
  5. slope and intercept form
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: September 10th 2006, 07:32 PM

Search Tags


/mathhelpforum @mathhelpforum