Question 166613
Refer to this site for a good explanation:
http://www.purplemath.com/modules/drofsign.htm
.
f(x)=-2x^5+3x^4-6x^2+1
There are three sign changes.
So, 3 or 1 positive roots
.
f(-x)=-2(-x)^5+3(-x)^4-6(-x)^2+1
f(-x)=2(x)^5+3(x)^4-6(x)^2+1
There are two sign changes.
So, 2 or 0 negative roots
.