Results 1 to 3 of 3

Math Help - Quadratic Equation Help

  1. #1
    Newbie
    Joined
    Dec 2010
    Posts
    2

    Quadratic Equation Help

    Hi, i'm very new to this forum and i am stuck on this problem. Perhaps i'm just having a brain freeze, but i'd like to know how to solve this question.Thanks . And apologies if this is in the wrong part of the forum.

    The height, h(t) metres, of a batted baseball as a function of the time, t seconds, since the ball was hit can be modelled by the function:

    h(t)=-2.1(t-2.4)^2 +13


    Question: How many seconds after it was hit did the ball hit the groud, to the nearest tenth of a second?

    The answer key tells me 4.9 seconds, however, i am unable to arrive at that answer. My idea was to substitute h(t) with 0 to get the x intercept, but the numbers greatly confused me.

    Any help? Thanks in advance
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    5
    h(t) = 0 the ball hits the ground.

    \displaystyle 0=-2.1(t-2.4)^2+13\Rightarrow \frac{13}{2.1}=(t-2.4)^2\Rightarrow\sqrt{\frac{13}{2.1}}+2.4=t

    \approx 4.888066
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Dec 2010
    Posts
    2
    gah. solved lol. thanks xD. i missed the square root step xP.
    Last edited by damocles; December 29th 2010 at 11:18 PM. Reason: hi
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. some quadratic equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: December 13th 2011, 09:29 PM
  2. Quadratic Equation
    Posted in the Algebra Forum
    Replies: 1
    Last Post: October 26th 2010, 02:11 PM
  3. Need Quadratic Equation
    Posted in the Algebra Forum
    Replies: 7
    Last Post: June 6th 2010, 04:31 PM
  4. Replies: 3
    Last Post: April 25th 2010, 04:53 PM
  5. Quadratic Equation
    Posted in the Algebra Forum
    Replies: 1
    Last Post: March 11th 2009, 08:34 AM

Search Tags


/mathhelpforum @mathhelpforum