要证原不等式只需证：x^k(y^(2n-k)-x^(2n-k))+y^k(x^(2n-k)-y^(2n-k))≤0；……（把右边移到左边,并提取公因式即得）只需证：(x^k-y^k)(y^(2n-k)-x^(2n-k))≤0下面对x,y的大小关系进行讨论.1.若x>y则 (x^k-y^k)>0,(y...