Results 1 to 3 of 3

Math Help - Had Make up test

  1. #1
    Newbie
    Joined
    Oct 2008
    Posts
    2

    Had Make up test

    So basically I had a make up test in Pre-Calc and right now I feel like ripping my hairs out for I have no idea if I got certain questions right. Any help will be appreciated. Thanks in advance

    From the top of my head I remembered certain questions such as:
    1) You have 2x^4+3x^3+7x^2-7x-5

    I had to find the root now was I supposed to use the basic p over q and plug in which were correct roots?

    2)This one killed me
    -4x^4+8x^3+7x*5
    I had to find the smallest root?

    3) This one also confused me and I could not answer. It gave me two roots 2+i and 3. I was supposed to find out the cubic polynomial. How exactly is this done?

    Thanks in advance for anyone who is willing to help.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member vincisonfire's Avatar
    Joined
    Oct 2008
    From
    Sainte-Flavie
    Posts
    469
    Thanks
    2
    Awards
    1

    Reply

    Root for the first polynomial are gonna be
    <br />
\frac {factors of 5}{root factors of 2} = \pm \frac{1}{2} \pm 1 \pm \frac{5}{2} \pm 5<br />
    In this case <br />
1 and \frac{-1}{2}<br />
    Solve number 2 and 3 with the same technique.
    Once a root works, use the division to get the next polynomial.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2008
    Posts
    147
    If a root is 2+i, then another root is 2-i, assuming that the polynomial has real coefficients. Then you have 3 roots, multiply the corresponding polynomials, such as (x-3), and you have your cubic polynomial.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: May 21st 2010, 10:56 AM
  2. Replies: 8
    Last Post: March 28th 2010, 06:45 PM
  3. Replies: 7
    Last Post: June 4th 2009, 10:33 PM
  4. Huh? Ratio test contradicts root test?
    Posted in the Calculus Forum
    Replies: 4
    Last Post: March 25th 2009, 01:07 PM
  5. ratio test (series) urgent test tommorow!
    Posted in the Calculus Forum
    Replies: 3
    Last Post: December 2nd 2008, 04:27 PM

Search Tags


/mathhelpforum @mathhelpforum