(a+b)²(b-a)的2n次方/(a-b)的2n-1次方=(a+b)²(a-b)的2n次方/(a-b)的2n-1次方=(a+b)²(a-b)的2n-(2n-1)次方=(a+b)²(a-b)=(a+b)(a+b)(a-b)=(a+b)(a²-b²)=a³-ab²+a²b-b
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