\(\left(x^2+2-1\right)^2-\left(x^2+2x+3\right)^2=\left(x^2+1\right)^2-\left(x^2+2x+3\right)=\left(x^2+1-x^2-2x-3\right)\left(x^2+1+x^2+2x+3\right)=-\left(2+2x\right)\left(2x^2+2x+4\right)=-2\left(x+1\right).2\left(x^2+x+2\right)=-4\left(x+1\right)\left(x^2+x+2\right)\)