y=x^3-x+5,
y'=3x^2-1,
3x^2-1=0,
x^2-1/3=0,
(x+1/√3)(x-1/√3)=0,
x_1=-1/√3,
x_2=1/√3∉[-4;0
x=-4, y=-55,
x=-1/√3, y=(45+2√3)/9≈5,4;
x=0, y=5.
min y=-55, x∈[-4;0]
