2n+1是奇数所以原式=-2(x-y)^2n+4(x-y)^2x+1=2(x-y)^2n[2(x-y)-1]=2(x-y)^2n(2x-2y-1)n奇数,原式=-a(y-x)^n-3b（y-x）^n+1+2c（y-x）^n+2=-(y-x)^n(a+3by-3bx+2cy²-4cxy+2cy²)n偶数,原式=a(y-x)^n-3b（y-x...