Results 1 to 11 of 11

Math Help - Word Problem

  1. #1
    Newbie
    Joined
    Oct 2008
    Posts
    8

    Unhappy Word Problem

    Hi, everyone. i'm new here. I hope someone can help me this. I really am not good in word problem.

    Janice wants to fence in a small garden area next to a stream.If she has 20 feet of fencing materials and doesn't fence the side bordering the stream, find the dimensions that will yield the maximum area and then find the maximum area she can enclose.
    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 Vkenny View Post
    Hi, everyone. i'm new here. I hope someone can help me this. I really am not good in word problem.

    Janice wants to fence in a small garden area next to a stream.If she has 20 feet of fencing materials and doesn't fence the side bordering the stream, find the dimensions that will yield the maximum area and then find the maximum area she can enclose.
    did you draw a diagram? let the side parallel the stream be x and the two sides perpendicular the stream be y.

    note that we have x + 2y = 20 amount of fence.

    the area is given by A = xy. this is what we want to maximize

    can you continue?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2008
    Posts
    8
    Quote Originally Posted by Jhevon View Post
    did you draw a diagram? let the side parallel the stream be x and the two sides perpendicular the stream be y.

    note that we have x + 2y = 20 amount of fence.

    the area is given by A = xy. this is what we want to maximize

    can you continue?
    i should do like this

    x+y=20
    x=20-2y then
    A=(20-2y)
    is this right
    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 Vkenny View Post
    i should do like this

    x+y=20
    x=20-2y then
    A=(20-2y)
    is this right
    no, if x = 20 - 2y and A = x*y, how do you get A = 20 - 2y, wouldn't that be the same as saying A = x, which we know is not true?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Oct 2008
    Posts
    8
    Quote Originally Posted by Jhevon View Post
    no, if x = 20 - 2y and A = x*y, how do you get A = 20 - 2y, wouldn't that be the same as saying A = x, which we know is not true?
    so i need to find a value of x and y in order to find the area.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    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 Vkenny View Post
    so i need to find a value of x and y in order to find the area.
    A = y(20 - 2y)

    this is a downward opening parabola. find the y-value of its vertex, that gives you the maximum. then you can find the corresponding x-value
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Oct 2008
    Posts
    8
    Quote Originally Posted by Jhevon View Post
    A = y(20 - 2y)

    this is a downward opening parabola. find the y-value of its vertex, that gives you the maximum. then you can find the corresponding x-value
    I'm sorry. i still didnt know how to solve this. how do you find y value.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    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 Vkenny View Post
    I'm sorry. i still didnt know how to solve this. how do you find y value.
    see post #4 here
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Newbie
    Joined
    Oct 2008
    Posts
    8
    Quote Originally Posted by Jhevon View Post
    see post #4 here
    is this right
    Y=5
    x=10
    then i completed the square
    A=-2(y-5)^2+25
    Follow Math Help Forum on Facebook and Google+

  10. #10
    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 Vkenny View Post
    is this right
    Y=5
    x=10
    yes

    then i completed the square
    A=-2(y-5)^2+25
    nope, it is -2(y - 5)^2 + 50
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Newbie
    Joined
    Oct 2008
    Posts
    8
    thank you so much. i understand it now.h
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. word problem - the snow plough problem?
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: October 13th 2011, 02:02 PM
  2. Replies: 3
    Last Post: January 2nd 2011, 09:20 PM
  3. 1 Word problem and 1 function problem
    Posted in the Algebra Forum
    Replies: 8
    Last Post: April 21st 2010, 09:01 AM
  4. Replies: 2
    Last Post: January 10th 2009, 06:49 AM

Search Tags


/mathhelpforum @mathhelpforum