问题
填空题
已知x+y=3,x2+y2-xy=4,那么x4+y4+x3y+xy3的值为______.
答案
∵x+y=3,x2+y2-xy=4,
∴x4+y4+x3y+xy3,
=x3(x+y)+y3(x+y),
=(x3+y3)(x+y),
=(x+y)(x2+y2-xy)(x+y),
=32×4,
=36.
故答案为:36.
已知x+y=3,x2+y2-xy=4,那么x4+y4+x3y+xy3的值为______.
∵x+y=3,x2+y2-xy=4,
∴x4+y4+x3y+xy3,
=x3(x+y)+y3(x+y),
=(x3+y3)(x+y),
=(x+y)(x2+y2-xy)(x+y),
=32×4,
=36.
故答案为:36.