I need help with this ... I don't understand it ..can anyone please help me with it .. It is due today

Answer:
1) x=0,2
2) x=2,-1
3) x =-2,1
4)x= -1
Step-by-step explanation:
Normal procedure for all polynomial :
1) [tex]\frac{df}{dx}=-3x^{2} +6x[/tex]
roots of this quadratic are =0 ,2
2) [tex]\frac{df}{dx}=3x^{2} +3x-6[/tex]
roots of this quadratic =2, -1
3) [tex]\frac{df}{dx}=3x^{3}+3x^{2} -6x[/tex]
Roots of this cubic =-2,1