25(x-y)2+10(y-x)+1.
问题描述:
25(x-y)2+10(y-x)+1.
答
25(x-y)2+10(y-x)+1
=[5(x-y)]2-2×1×5(x-y)+12
=[5(x-y)-1]2
=(5x-5y-1)2.