x^2+(x^2)[(x+1)^2]+(x+1)^2
=x^2+x^2[x^2+2x+1]+(x^2+2x+1)
=x^2+x^4+2x^3+x^2+x^2+2x+1
=(x^4+2x^3+x^2)+(2x^2+2x)+1
=(x^2+x)^2+2(x^2+x)+1
=(x^2+x+1)^2