• Oct 19th 2008, 04:26 PM
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.
• Oct 19th 2008, 05:24 PM
vincisonfire
Root for the first polynomial are gonna be
$
\frac {factors of 5}{root factors of 2} = \pm \frac{1}{2} \pm 1 \pm \frac{5}{2} \pm 5
$

In this case $
1 and \frac{-1}{2}
$

Solve number 2 and 3 with the same technique.
Once a root works, use the division to get the next polynomial.
• Oct 19th 2008, 05:32 PM
terr13
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.