(x+y的2n-1次方) 乘以 (-x-y的6次方)+(x+y的n+3次方) 乘以 (x+y的n+2次方)=(x+y)^(2n-1) ×(x+y)^6+(x+y)^(n+3) ×(x+y)^(n+2)=(x+y)^(2n-1+6)+(x+y)^(n+2+n+3)=(x+y)^(2n+5)+(x+y)^(2n+5)=2(x+y)^(2n+5)希望能帮到...