Results 1 to 2 of 2

Thread: [SOLVED] equation

  1. #1
    Member
    Joined
    Aug 2009
    Posts
    211

    [SOLVED] equation

    hi, i've got the question-

    find the range of values of the constant c for which the line $\displaystyle y = 3x + c$ does not intersect the parabola with equation $\displaystyle y = 2x^2 + 5x - 7$

    i know you have to have a discriminant thats less than 0 for this so i strted by putting the equation into one like this $\displaystyle 2x^2 + 2x + (-7 - c)$ so then used the theory : $\displaystyle (2)^2 - 4(2)(-7-c)$ which came to $\displaystyle 4 - (- 56 - 8c)$ which then became $\displaystyle (60 - 8c) < 0$ then i made it $\displaystyle - 8c < - 60$ leaving $\displaystyle c < 7.5$.

    the answer the book gives me is $\displaystyle c < - 7.5$

    can some explain this please? thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Aug 2009
    Posts
    211
    ah i just realised, i should have made it + 8c rather than - 8c
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Can this equation be solved for F?
    Posted in the Algebra Forum
    Replies: 5
    Last Post: Sep 15th 2011, 08:37 AM
  2. Replies: 2
    Last Post: May 23rd 2010, 10:46 AM
  3. [SOLVED] Help w/ an equation please
    Posted in the Algebra Forum
    Replies: 3
    Last Post: Mar 5th 2009, 06:44 PM
  4. [SOLVED] Log equation help,
    Posted in the Algebra Forum
    Replies: 4
    Last Post: Feb 14th 2009, 09:08 PM
  5. [SOLVED] Equation Help
    Posted in the Algebra Forum
    Replies: 1
    Last Post: Feb 7th 2008, 02:20 AM

Search Tags


/mathhelpforum @mathhelpforum