`#DyHungg`
`(1/(x^2+4x+4)-1/(x^2-4x+4)):(1/(x+2)+1/(x+2)) ĐKXĐ: x \ne ±2`
`=(1/((x+2)^2)-1/((x-2)^2)):2/(x+2)`
`=((x-2)^2-(x+2)^2)/((x-2)^2.(x+2)^2) . (x+2)/2`
`=((x-2-x-2)(x-2+x+2))/((x-2)^2.(x+2)^2) . (x+2)/2`
`=(-4.2x)/((x-2)^2.(x+2)^2) . (x+2)/2`
`=(-8x)/((x-2)^2.(x+2)^2) . (x+2)/2`
`=(-4x)/((x-2)^2.(x+2))`
`=(-4x)/((x^2-4x+4)(x+2))`
`=(-4x)/(x^3-2x^2-4x+8)`