(1) 9x^(n+1)-36x^n+36x^(n-1) =9x^(n-1)(x²-4x+4)=9x^(n-1)(x-2)²(2) 应该是2(2x-1)^2-4/3(2x-1)+2/9=2[(2x-1)²-2/3(2x-1)+1/9]=2(2x-1-1/3）²=2(2x-4/3)²