Q:

According to Descartes' rule of signs, how many possible negative real roots could the following polynomial function have? f(x)=3x^4-5x^3+5x^2+5x+2A. Three or oneB. ThreeC. OneD. Two or Zero

Accepted Solution

A:
f(-x)=3(-x)^4-5(-x)^3+5(-x)^2+5(-x)+2
=3x^4+5x^3+5x^2-5x+2
=+        +        +      -     +
there are two changes of sign
so at the most two negative real roots