For your first post.Note;

if 0<|y|<1

then |y^n|<|y^m| and n>m

if -1<y<0

then |y^3|<|y^2| and y^3<y^2 regardless of sign

|y^4|<|y^2| and y^4<y^2 regardless of sign

y,y^3 are -ve, y^2,y^4 are positive

so y<y^3<y^4<y^2

You could just plug in y=-0.5 and it will tell you which is bigger