x^3=3y^2x+5-√7y^3=3x^2y+5+√7,则x^2+y^2＝

更新时间2019-12-29 11:13:30

|x+y+7|+(xy-5)^2=0,则 x+y+7=0,x+y=-7,xy-5=0,xy=5,所以 3x^2y^3+3x^3y^2 =3x^2y^2(y+x) =3*(xy)^2*(x+y) =3*5^2*(-7) =3*25*(-7) =-525