Question

已知|xy-2/3|+(y+1)平方=0,求x-2(xy+1/3y平方)-(3/2-2/3y平方)的值

Answer 1

|xy-2/3|+(y+1)平方=0

xy-2/3=0
y+1=0

x=-2/3
y=-1

x-2(xy+1/3y平方)-(3/2-2/3y平方)
=x-2xy-2/3y平方-3/2+2/3y平方
=x-2xy-3/2
=-2/3-4/3+3/2
=-1/2

Answer 2

|xy-2/3|+(y+1)平方=0
|xy-2/3|=0，(y+1)平方=0
y+1=0
xy-2/3=0
y=-1
-x-2/3=0
x=-2/3

x-2(xy+1/3y平方)-(3/2-2/3y平方)
=x-2xy-2/3y平方-3/2+2/3y平方
=x-2xy+2/3y平方-2/3y平方-3/2
=x-2xy-3/2
=-2/3-2*(-2/3)*(-1)-3/2
=-2/3-4/3-3/2
=-2-3/2
=-7/2

Answer 3

∵|xy-2/3|≥0
(y+1)²≥0
又∵|xy-2/3|+(y+1)²=0
∴|xy-2/3|=0
(y+1)²=0
∴y=-1
x=-2/3
∴x-2(xy+1/3y平方)-(3/2-2/3y平方)
=-2/3-2(2/3+1/4)-(3/2-1)
=-2-2+1
=-3

Answer 4

|xy-2/3|+(y+1)^2=0 => xy=2/3 ;y=-1 => x=-2/3
=> x -2(xy+ 1/3y^2) -(3/2 -2/3y^2)=x-2(-x)-3/2 +2/3 =3x-3/2+2/3=-2-3/2+2/3=7/6

Answer 5

xy=2/3,y=-1,所以x=-2/3
-2/3-2(2/3+1/3)-(3/2-2/3)=-7/2