Thực hiện phép tính: 1/(x^2+3x+2)- 2x/(x^3+4x^2+4x)+1/(x^2+5x+6)

1x2+3x+2−2xx3+4x2+4x+1x2+5x+6

=1x2+2x+x+2−2xx(x2+4x+4)+1x2+3x+2x+6=1x(x+2)+(x+2)−2xx(x+2)2+1x(x+3)+2(x+3)=1(x+2)(x+1)−2xx(x+2)2+1(x+3)(x+2)=x(x+2)(x+3)x(x+1)(x+2)2(x+3)−2x(x+1)(x+3)x(x+1)(x+2)2(x+3)+x(x+1)(x+2)x(x+1)(x+2)2(x+3)=x(x+2)(x+3)−2x(x+1)(x+3)+x(x+1)(x+2)x(x+1)(x+2)2(x+3)=x3+5x2+6x−2x3−8x2−6x+x3+3x2+2xx(x+1)(x+2)2(x+3)=2xx(x+1)(x+2)2(x+3)=2(x+1)(x+2)2(x+3).