Y=x^3-2x^4+x-3 на отрезке [-4; -1/3] можно подробное решение?

Y=x³-2x⁴+x-3;[-4;-1/3]

1)y'=3x²-4x³+1
y'=0
3x²-4x³+1=0
3x²-3x³-x³+1=0

3x²(1-x)+(1-x)(1+x+x²)=0
(1-x)(3x²+1+x+x²)=0
1-x=0;x=1¢[-4;-1/3]
4x²+x+1=0
D=1-16=-15<0
x€∅
2)y(-4)=-64-2*216-4-3=-64-432-7=-503
y(-1/3)=-1/27-4*1/81-1/3-3=
(-3-4-27-243)/81=
-277/81=-3 *34/81
y(-4) min
y(-1/3) max