Question

More help, please??
Using complete sentences, explain how the Rational Root Theorem and Descartes’ Rule of Signs are used to find the zeros of a polynomial function.

Answer 1

i don't know about rational root theorem

but

Descartes’ Rule of Signs is very simple.

you take a polynomial, and see number of sign variation in the equation.

then that many positive real roots will be there.

eg: x^3-x^2+x-3=0

sign change like + - + -

there are three changes, so there are 3 positive roots.

next you replace x by -x(x-----> -x)

then for that equation number of change in sign results the number of negative roots.

so in the given eg: replace x by -x

-x^3-x^2-x-3=0

so sign change is like - - - -

that is no change => no negative roots.

so this way we can find no. of positive and negative real roots and remaining are complex.

Answer 2

Thank you so so much! you were a great help! :D

Answer 3

no problem :)