解析
x²-xy=4
y²-xy=9
x²-2xy+y²=(x²-xy)+(y²-xy)
=4+9
=13
x²-y²=(x²-xy)-(y²-xy)
=4-9
=-5
希望对你有帮助
学习进步O(∩_∩)O谢谢在详细点啊x²-2xy+y²=(x²-xy)+(y²-xy)=x²-xy+y²-xy=4+9=13x²-y²=(x²-xy)-(y²-xy)=x²-xy-y²+xy=x²-y²-2xy=4-9=-5