Results 1 to 12 of 12

Math Help - Help with equations of lines.

  1. #1
    Newbie
    Joined
    Nov 2010
    Posts
    8

    Help with equations of lines.

    can someone answers these please? These are the ones i got wrong on a test and i ant to know the write answers so i can do better


    1. Write an equation for the line that has slope 5/3 and intersects the y-axis at -6

    2. A hang glider takes off from an 800-ft cliff. After 5 minutes he is at an altitude of 500 ft.

    A. Determine the rate of change

    B. Write a linear equation to model the situation


    3. Rewrite -3x+6y=12 in slope intercept form

    4. Write an equation in point-slope form of the line passing through (-2,6) with slope -5/7

    5, The line perpindiuclar to y=-3x-1 has a slope of....

    6. Write an equation of the line parrallel to y=-1/2x+9
    Last edited by mr fantastic; March 13th 2011 at 02:26 PM. Reason: Re-titled.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    16,394
    Thanks
    1845
    Quote Originally Posted by ineedhelplol View Post
    can someone answers these please? These are the ones i got wrong on a test and i ant to know the write answers so i can do better


    1. Write an equation for the line that has slope 5/3 and intersects the y-axis at -6
    A line with slope m can be written in the form y= mx+ b. And, of course, the line crosses the y-axis when x= 0 so y= m(0)+ b= b.

    2. A hang glider takes off from an 800-ft cliff. After 5 minutes he is at an altitude of 500 ft.

    A. Determine the rate of change
    So he went from 800 to 500. How many feet did he go up (be careful of the sign). And he did that in 5 minutes. How many feet per minute is that?

    B. Write a linear equation to model the situation
    Again, y= mx+ b (x is the time in minutes here). You got the slope, m, in (A) and when x= 0 y= 800.


    3. Rewrite -3x+6y=12 in slope intercept form
    "Slope intercept form" is "y= mx+ b". Solve for y.

    4. Write an equation in point-slope form of the line passing through (-2,6) with slope -5/7
    Again, y= mx+ b.

    5, The line perpindiuclar to y=-3x-1 has a slope of....
    If m1 and m2 are the slopes of two perpendicular lines, then m1m2= -1.

    6. Write an equation of the line parrallel to y=-1/2x+9
    Surely the problem did not say "the" line. There are an infinite number of lines parallel to this or any line. Two lines are parallel if and only if they have the same slope.
    Last edited by mr fantastic; March 13th 2011 at 02:13 PM. Reason: Fixed a quote tag.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Nov 2010
    Posts
    8
    Can you answer them for me please? And yes my bad it didnt say the line.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    12,106
    Thanks
    970
    Quote Originally Posted by ineedhelplol View Post
    i just need to know the answers
    Sorry, but that it not how it works here at MHF ... Halls of Ivy has provided you the necessary guidance to find the solutions yourself. Post your work and solutions to get further guidance if necessary.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Nov 2010
    Posts
    8
    1. y=5/3x-6

    2. A. 300/50=60/1

    B. ?

    3. y=-1/2x+2

    4. y-2=-5/7(x+6)

    5. 1/3

    6.y=-1/2x=8



    are these right?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ineedhelplol View Post
    1. y=5/3x-6 Mr F says: Yes.

    2. A. 300/50=60/1 Mr F says: Wrong sign.
    B. ? Mr F says: Review the help you were given. What have you tried? Where are you stuck?

    3. y=-1/2x+2 Mr F says: No. Do it more carefully.

    4. y-2=-5/7(x+6) Mr F says: No. Does it pass through (-2, 6)? Go back and use the slope-point formula more carefully.

    5. 1/3 Mr F says: Yes.

    6.y=-1/2x=8 Mr F says: Yes.

    are these right?
    Most of your errors are careless mistakes.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Nov 2010
    Posts
    8
    2. A. -60/1
    B. 800=-60x-500?

    3. ?

    4. y-6=-5/7(x-(-2)
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ineedhelplol View Post
    2. A. -60/1 Mr F says: Yes.
    B. 800=-60x-500? Mr F says: This is not the equation of a line. Go back and read the help you were given.

    3. ? Mr F says: See previous feedback.

    4. y-6=-5/7(x-(-2) Mr F says: Yes. But another bracket is need at the end. And yuor teacher may want it in y = mx + c form.
    ..
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Newbie
    Joined
    Nov 2010
    Posts
    8
    y = -300/800x + 0

    is that the answer to 2b?
    Follow Math Help Forum on Facebook and Google+

  10. #10
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ineedhelplol View Post
    y = -300/800x + 0

    is that the answer to 2b?
    For goodness sake! Stop guessing and read what you were told in post #2.
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Newbie
    Joined
    Nov 2010
    Posts
    8
    800=-60/1x+0

    thats gotta be it.
    Follow Math Help Forum on Facebook and Google+

  12. #12
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ineedhelplol View Post
    800=-60/1x+0

    thats gotta be it.
    That's NOT an equation that relates height to time.

    You have already shown some understanding of using the slope-point form y - y1 = m(x - x1). I do not know why you can't correctly apply it here.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. equations of lines
    Posted in the Algebra Forum
    Replies: 24
    Last Post: September 16th 2011, 01:02 PM
  2. I need help /w equations of some lines
    Posted in the Calculus Forum
    Replies: 3
    Last Post: August 2nd 2008, 12:31 PM
  3. Equations of Lines
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: March 17th 2008, 07:20 PM
  4. Equations of Lines
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: May 3rd 2007, 09:58 PM
  5. equations of lines
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 21st 2007, 08:59 AM

Search Tags


/mathhelpforum @mathhelpforum