Results 1 to 8 of 8

Math Help - Word Problem Equations

  1. #1
    Newbie
    Joined
    Jan 2010
    Posts
    10

    Word Problem Equation:1st try

    I'm completely lost with this one....

    A company charting its profits notices that the relationship between the number of units sold, x, and the profit, P is linear. If 300 units sold results in $4650 profit and 375 units results in $9000 profit write the equation that models the profit.

    What I got was 4350x-1300350

    using the y-y1=m(x-x1)
    Last edited by Annb; February 20th 2010 at 06:28 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member integral's Avatar
    Joined
    Dec 2009
    From
    Arkansas
    Posts
    200
    I got
    y=58x-12750


    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jan 2010
    Posts
    10
    How did you get that answer? : (
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,099
    Thanks
    67
    Quote Originally Posted by Annb View Post
    A company charting its profits notices that the relationship between the number of units sold, x, and the profit, P is linear. If 300 units sold results in $4650 profit and 375 units results in $9000 profit write the equation that models the profit.
    What I got was 4350x-1300350
    using the y-y1=m(x-x1)
    Huh?
    You have 2 points: (300,4650) and (375,9000)

    linear equation using 2 points - Google Search=
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member integral's Avatar
    Joined
    Dec 2009
    From
    Arkansas
    Posts
    200
    y=ax+b
    y_i=ax_i+b


    <br /> <br />
y=4650<br />
    x=300
    y_i=9000
    x_i=375

    subtract both equations, cancel B out
    y-y_i=a(x-x_i)

    -4350=-75a
    a=\frac{-4350}{-75}=58

    place a in an orig. equation
    y=ax+b
    <br />
4650=58(300)+b=17400+b
    4650-17400=b
    b=-12750

    plug in

    y=58x-12750
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Senior Member
    Joined
    Jul 2009
    From
    Melbourne
    Posts
    272
    Thanks
    4
    Most simple way:

    \frac{y-y_{1}}{x-x_{1}} = \frac {y_{2}-y_{1}}{x_{2}-x_{1}}

    Substitute values in to get

     75y-348750=4350x-1631250

    Divide 75 to get

    y-4650=58x-21750

     y+17100=58x

     y=58x-17100 In the form of y=mx+c

    My answer is different to integrals's but this is just to let you know you can use the 2 point formula.
    Last edited by jgv115; February 21st 2010 at 02:32 AM.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,419
    Thanks
    1330
    Quote Originally Posted by jgv115 View Post
    Most simple way:

    \frac{y-y_{1}}{x-x_{1}} = \frac {y_{2}-y_{1}}{x_{2}-x_{1}}

    Substitute values in to get

     75y-348750=4350x-1631250

    Divide 75 to get

    y+8550-19x
    You've lost a "="!
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Senior Member
    Joined
    Jul 2009
    From
    Melbourne
    Posts
    272
    Thanks
    4
    corrected =]
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. 3 Trig Equations and 1 Word Problem Help
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: May 3rd 2009, 10:56 PM
  2. HELP!polynomials:word problem equations
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 19th 2009, 04:59 AM
  3. Differential Equations Word Problem...
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: March 12th 2009, 05:20 AM
  4. System-of-Equations Word Problem..
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 21st 2008, 02:19 AM
  5. word problem equations
    Posted in the Algebra Forum
    Replies: 11
    Last Post: February 15th 2008, 05:15 PM

Search Tags


/mathhelpforum @mathhelpforum