Răspuns:
Explicație pas cu pas:
E(x)=[(x+2)+(x-1)]*[(x+2)-(x-1)]-2x-6-5=
=(x+2+x-1)*(x+2-x+1)-2x-11=
=(2x+1)*3-2x-11=
=6x+3-2x-11=
=4x-8=
=4*(x-2)