已知x(x+1)-(x^2-y)=-3,求2分之x^2+y^2+xy的值

已知x(x+1)-(x^2-y)=-3,求2分之x^2+y^2+xy的值
已知x(x+1)-(x^2-y)=-3,求2分之x^2+y^2+xy的值

已知x(x+1)-(x^2-y)=-3,求2分之x^2+y^2+xy的值
x(x+1)-(x^2-y)=3
x^2+x-x^2+y=3
x+y=3
(x^2+y^2)/2+xy
=[(x+y)^2-2xy]/2+xy
=(x+y)^2/2-xy+xy
=(x+y)^2/2
=3^2/2
=9/2