已知x2+xy=5,xy+y2=-1,则x2-y2=_.
问题描述:
已知x2+xy=5,xy+y2=-1,则x2-y2=______.
答
∵x2+xy=5,xy+y2=-1,
∴(x2+xy)-(xy+y2)
=x2+xy-xy-y2
=x2-y2
=5-(-1)
=6.
故填:6