x^（a+3）-x^ay^3=x^ax^3-x^ay^3=x^a(x³-y³)=x^a(x-y)(x²+xy+y²)注：x³-y³=(x-y)(x²+xy+y²)这是我在静心思考后得出的结论,如果不能请追问,我会尽全力帮您解决的~如果您有所...