Results 1 to 2 of 2

Math Help - quadradic inequality

  1. #1
    Newbie
    Joined
    Jun 2007
    Posts
    22

    Unhappy quadradic inequality

    Find f(3a) of f(x)= -2x^2 + 3x - 4
    and

    The Solutions to 6m^2 - 7m + 1 = 0 <br />
    and

    This is the equation used ot express the amount of items a business has at a given time. T = months.

     <br />
N(t) = 5t^3 - 70t^2 + 245t <br />
    0<_ t <_ 10

    Find when there are no items left..


    PLEASE HELP!
    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 mibamars View Post
    Find f(3a) of f(x)= -2x^2 + 3x - 4
    and
    For questions like these, you just plug in whatever they put in brackets in the position that x is in.

    f(x) = -2x^2 + 3x - 4

    \Rightarrow f(3a) = -2(3a)^2 + 3(3a) - 4

    And you just simplify that

    The Solutions to 6m^2 - 7m + 1 = 0 <br />
    This is a relatively simple quadratic equation to solve, just foil.

    6m^2 - 7m + 1 = 0

    \Rightarrow (6m - 1)(m - 1) = 0

    \Rightarrow m = \frac {1}{6} \mbox { or } m = 1

    This is the equation used ot express the amount of items a business has at a given time. T = months.

     <br />
N(t) = 5t^3 - 70t^2 + 245t <br />
    0<_ t <_ 10

    Find when there are no items left..
    This qustion is simply asking to solve the quadratic equation

    0 = 5t^3 - 70t^2 + 245t ...........factor out the common 5t

    \Rightarrow 0 = 5t(t^2 - 14t + 49) ..............now foil the last quadratic

    \Rightarrow 0 = 5t (t - 7)(t - 7) ..............simplify a bit

    \Rightarrow 0 = 5t(t - 7)^2

    \Rightarrow 5t = 0 \mbox { or } (t - 7)^2 = 0

    \Rightarrow t = 0 \mbox { or } t = 7

    t = 0 is trivial, so we take \boxed { t = 7}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. quadradic
    Posted in the Algebra Forum
    Replies: 1
    Last Post: September 20th 2008, 11:10 AM
  2. quadradic
    Posted in the Algebra Forum
    Replies: 4
    Last Post: September 18th 2008, 06:43 PM
  3. fit to quadradic
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: May 10th 2008, 10:10 PM
  4. quadradic
    Posted in the Algebra Forum
    Replies: 4
    Last Post: March 31st 2008, 01:06 AM
  5. quadradic
    Posted in the Algebra Forum
    Replies: 1
    Last Post: January 15th 2008, 02:45 PM

Search Tags


/mathhelpforum @mathhelpforum