Question

According to Descartes' rule of signs, how many possible positive real roots could the following polynomial function have?

f(x)=3x^4-5x^3+5x^2+5x-2

A. Four
B. Three
C. Two or zero
D. Three or one

Answer 1

What does Descartes' rule of signs say?

Answer 2

I dont know..

Answer 3

You should really look up the rule, it's pretty simple. All you do is literally count

Answer 4

oh ok cool thanks :)

Answer 5

Well, I think I can explain it in one post...you count the number of times the signs consecutively change in between terms, like if the sign goes from positive to negative or negative to positive. That will tell you how many possible real roots there are

Answer 6

oh wow cool thanks! :)

Answer 7

is it D?

Answer 8

i dont think its C

Answer 9

Or A

Answer 10

How many sign changes do you see, and between which terms are the sign changes?

Answer 11

3

Answer 12

so its B

Answer 13

Well, that's not all there is to Descartes' rule of signs. You have to count down by twos because of the nature of arriving at the solutions (by using the quadratic equation). So there can be 3, or 1 (count down by 2 from 3) positive real roots

Answer 14

oh ok so it can be D