# Any help today would be appreciated, thanks.

1. Sep 11, 2009

1. The problem statement, all variables and given/known data
wtihout using a graphing calc, find the rational roots of P(x) = 2x^4-5x^3+5x^2-5x+3

2. Relevant equations

3. The attempt at a solution

The answers are 1 and 3/2, because this is a homework question. I dont know how they got that though. If anybody can help me today that would be appreciated.

Thanks,

2. Sep 11, 2009

### gabbagabbahey

Hint: Look up the "rational root theorem"

3. Sep 11, 2009

### Dick

4. Sep 11, 2009

### HallsofIvy

Staff Emeritus
If that isn't clear (thanks, Dick) the rational root theorem says that any rational root of $a_ix^i+ a_{i-1}x^{i-1}+ \cdot\cdot\cdot+ a_1x+ a_0$ must be of the form m/n where m divided $a_i$ and n divides $a_0$ (that's because if x= m/n is root then (x- m/n)= (1/n)(nx- m) must be a factor). Here, $a_n= a_4= 2$ and $a_0= 3$. Since those are prime, there are not a whole lot of possiblities.