Ngo Minhnam's Profile

x(x+2)(x^2+2x+2)+1
=(x^2+2x)(x^2+2x+2)+1

đặt x^2+2x=a

=>a(a+2)+1

=a^2+2a+1

=(a+1)²

^{=(x^2+2x+1)^2}

^{=((x+1)^2)^2}