x²-xy=8,xy-y²=3,求x²-2xy+y²

问题描述:

x²-xy=8,xy-y²=3,求x²-2xy+y²

x²-2xy+y²
=x²-xy-xy+y²
=(x²-xy)-(xy-y²)
=8-3
=5这位仁兄,对不对呢