a) f'(x) =3x^2+3x <0
3x*(x+1)<0
x=0 x+1=0
x=-1
(-1;0)
b)f'(x)=4-1/3*3x^2 = 4-x^2<0
x^2-4>0
(x-2)(x+2)>0
x=2 x=-2
(-oo;-2)U(2;+oo)
a) f'(x) =3x^2+3x <0
3x*(x+1)<0
x=0 x+1=0
x=-1
(-1;0)
b)f'(x)=4-1/3*3x^2 = 4-x^2<0
x^2-4>0
(x-2)(x+2)>0
x=2 x=-2
(-oo;-2)U(2;+oo)