~ Bạn tham khảo ~
`a, x^3(2+x)^2 - (x+2)^2 + 1-x^3`
`= (x+2)^2(x^3-1)-(x^3-1)`
`=(x^3-1)[(x+2)^2-1]`
`=(x-1)(x^2+x+1)(x+2-1)(x+2+1)`
`=(x-1)(x^2+x+1)(x+1)(x+3)`
`b, x(x-y)^2+y(x-y)^2-xy+x^2`
`= (x-y)^2(x+y)+x(x-y)`
`= (x-y)[(x-y)(x+y)+x]`
`=(x-y)(x^2-y^2+x)`