Results 1 to 5 of 5

Math Help - finding the eqn of a straight line

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    23

    finding the eqn of a straight line

    A straight line crosses the x-axis at x = 3 and the y-axis at y = −3. Find the equation of the line. Please give your answer in the functional form:
    y = a x + b
    for some constants a and b.

    I know what b is, (-3) but how do I find a? please can someone help?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1574
    Awards
    1
    Quote Originally Posted by [nuthing] View Post
    A straight line crosses the x-axis at x = 3 and the y-axis at y = −3. Find the equation of the line. Please give your answer in the functional form: y = a x + b for some constants a and b.
    If we know that neither p\text{ nor }q is zero then the points (p,0)~\&~(0,q) determine the line
    \dfrac{x}{p}+\dfrac{y}{q}=1.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,423
    Thanks
    1331
    Quote Originally Posted by [nuthing] View Post
    A straight line crosses the x-axis at x = 3 and the y-axis at y = −3. Find the equation of the line. Please give your answer in the functional form:
    y = a x + b
    for some constants a and b.

    I know what b is, (-3) but how do I find a? please can someone help?
    When x= 3 y= 0 so 0= 3a+ b. When x= 0, y= -3 so -3= 0a+ b. That second equation tells you that b= -3. Now put that into the first equation and solve for a.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Nov 2007
    From
    Trumbull Ct
    Posts
    905
    Thanks
    27
    the slope of the line is 1 and the y intercept is -3 so y=x-3


    bjh
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,423
    Thanks
    1331
    Quote Originally Posted by bjhopper View Post
    the slope of the line is 1 and the y intercept is -3 so y=x-3


    bjh
    I would have preferred that [nuthing] be allowed to finish the problem himself.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding the equation of a straight line.
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 9th 2011, 05:24 PM
  2. Finding the equation of the straight line
    Posted in the Geometry Forum
    Replies: 7
    Last Post: October 18th 2010, 07:21 AM
  3. finding Vo and r from a straight line graph
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 9th 2009, 06:57 AM
  4. Finding the equation of a straight line
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: February 28th 2009, 05:57 PM
  5. Replies: 1
    Last Post: February 28th 2009, 06:56 AM

Search Tags


/mathhelpforum @mathhelpforum