已知实数a.b.x.y满足a b=x y=2,ax+by=5,则(a^2+b^2)xy+ab(x^2+y^2)=?

20--------------------------ax+by=5ax*by=axby=ab*xy=4解方程组得:ax=4,by=1或ax=1,by=4(a^2+b^2)xy+ab(x^2+y^2)=a^2xy+b^2xy+abx^2+aby^2=(ax+by)(ay+bx)=5(ay+bx)没时间了,下次再写完