Results 1 to 5 of 5

Math Help - Quadratic Problem.

  1. #1
    Junior Member
    Joined
    Sep 2008
    Posts
    43

    Post Quadratic Problem.


    Ok this is what the problem is

    In 1900, one of the most devastating hurricanes in the United States occurred in Galveston. The people of the city had prior warning, but many waited to leave the island until teh streets and the only bridge were covered with 4 feet of water. The winde speed reached 220 mph. Five foot waves destroyed wooden buildings and carried the occupants out to the sea. Use your equation to find a level for hurricanes reaching this wind speed.

    Level - Maximum Wind Speed(mph)
    1 - 95
    2 - 110
    3 - 130
    4 - 155

    The equation i found was y=2.5x^2+7.5x+85

    My teach said plug 220 into it like so:
    220=2.5x^2+7.5x+85
    -220 -220

    0=2.5x^2+7.5x-135

    Now im lost... anyone know how to do this?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie Firstone's Avatar
    Joined
    May 2008
    Posts
    20
    You just have to solve for X now, by the quadratic formula
    Last edited by Firstone; September 10th 2008 at 03:13 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Banned
    Joined
    Aug 2008
    Posts
    530
    Quote Originally Posted by jemadd2 View Post

    Ok this is what the problem is

    In 1900, one of the most devastating hurricanes in the United States occurred in Galveston. The people of the city had prior warning, but many waited to leave the island until teh streets and the only bridge were covered with 4 feet of water. The winde speed reached 220 mph. Five foot waves destroyed wooden buildings and carried the occupants out to the sea. Use your equation to find a level for hurricanes reaching this wind speed.

    Level - Maximum Wind Speed(mph)
    1 - 95
    2 - 110
    3 - 130
    4 - 155

    The equation i found was y=2.5x^2+7.5x+85

    My teach said plug 220 into it like so:
    220=2.5x^2+7.5x+85
    -220 -220

    0=2.5x^2+7.5x-135

    Now im lost... anyone know how to do this?
    2.5x^2+7.5x-135=0

    Divide the equation by 2.5, we get,

    x^2+3x-54=0

    (x+6)(x-3)=0

    x= -6, x=3
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Sep 2008
    Posts
    43

    Post

    thanks for that but i will get two answers when i do that because of the + i will get 1350 for + and
    i will get 1335 for - what do i do with these two? divide?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Sep 2008
    Posts
    43

    A little more help?

    I did a guess check and found that 6 works with it... which would make it

    LEVEL=Mph
    6=220mph

    If someone knows how to figure out x when y is given. plz post for me.

    P.S. i need 1 answer. not x=?,x=?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] quadratic equation, A.P. and G.P. related problem problem
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: August 20th 2011, 09:43 AM
  2. Quadratic problem...!
    Posted in the Algebra Forum
    Replies: 10
    Last Post: July 19th 2011, 03:18 PM
  3. quadratic problem
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 26th 2010, 05:12 AM
  4. quadratic problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 26th 2009, 02:55 AM
  5. quadratic problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 26th 2008, 06:19 PM

Search Tags


/mathhelpforum @mathhelpforum