Answer:
{-1, -1/3, 1/3, 1}
Step-by-step explanation:
The possible rational roots are ...
±(divisor of constant)/(divisor of leading coefficient)
Here, that means the rational roots are ...
±p/q where p ∈ {1}, and q ∈ {1, 3}
That is, they can be ±1/1 or ±1/3. Arranged from smallest to largest, they are ...
-1, -1/3, 1/3, 1
_____
A graph shows the roots to be -1 (multiplicity 2) and (+1/3). Then the function factors as ...
f(x) = (3x -1)(x +1)²
