y'=( 1+x)？ +2x( 1+x)=( 1+x)( 1+3x)

Extreme point x=- 1,-1/3.

Monotone increasing interval: x

Monotone subtraction interval:-1

F(- 1)=0 is the maximum value.

F(- 1/3)=-4/27 is the minimum value.

y " = 1+3x+3( 1+x)= 6x+4 = 2(3x+2)

The inflection point x=-2/3.

F(-2/3)=-2/27, that is, the inflection point is (-2/3, -2/27).

Convex interval: x

Concave interval: x & gt-2/3