已知实数x,y满足|x+y+7|+(xy-5)^2=0,求3x^2y^3+3x^3y^2_数学解答

已知实数x,y满足|x+y+7|+(xy-5)^2=0,求3x^2y^3+3x^3y^2

人气：187 ℃　时间：2019-08-20 04:03:34

解答

|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