1)lim(x2-4)/(x+2)=lim(x+2)(x-2)/(x+2)=lim(x-2)=-4
2)lim(1+x3)/2x3=lim(1/2x3+x3/2x3)=Lim(1/2x3)+lim(x3/2x3)=0+1/2
3)-1