Using complete sentences, describe how you would analyze the zeros of the polynomial function f(x) = -3x5 - 8x4 +25x3 - 8x2 +x - 19 using Descartes' Rule of Signs.

Be sure to provide the answer in your explanation.

Question

Using complete sentences, describe how you would analyze the zeros of the polynomial function f(x) = -3x5 - 8x4 +25x3 - 8x2 +x - 19 using Descartes' Rule of Signs.

Be sure to provide the answer in your explanation.

anonymous · Answer

the coefficients of $f$ have 4 changes of sign 
from -8 to 25, from 25 to -8, from -8 to 1 and from 1 to -19 so there are either 4, 2 or no positive zeros

anonymous · Answer

$f(-x)=3x^5-8x^4-25x^3-8x^2-8x-19$ and this has 1 change i sign, from 3 to -8
so it has one negative zero

anonymous · Answer

how you are supposed to find them is anybody's guess, since there is no formula for a polynomial of degree 5
it turns out this one has one negative zero and that is all

anonymous · Answer

okay, thank you.. This stuff just confuses me. thanks XD

anonymous · Answer

i can't imagine how you were supposed to solve this i did this http://www.wolframalpha.com/input/?i=-3x5+-+8x4+%2B25x3+-+8x2+%2Bx+-+19+