UC知道初一数学题~~急
来源：百度知道 编辑：UC知道 时间：2024/07/08 01:48:53
化简：x^2-{5x-[x^2-2(3-3x)]}
已知（x+3)^2+|y-1|=0求xy^2-2x^2y+[2xu^2-93xy^2-x^2y)]
已知x=-1,y=-2,z=1/3,求x^2y-[-x^2y+(xyz-x^2z)+xyz]-x^2z
先化简,再求值;1/2x-(2x-2/3y^2)+(-3/2x+1/3y^2),之中x=-1/3,y=-2
已知（x+3)^2+|y-1|=0求xy^2-2x^2y+[2xu^2-93xy^2-x^2y)]
已知x=-1,y=-2,z=1/3,求x^2y-[-x^2y+(xyz-x^2z)+xyz]-x^2z
先化简,再求值;1/2x-(2x-2/3y^2)+(-3/2x+1/3y^2),之中x=-1/3,y=-2
1.-{5x-[x²-2(3-3x)]}
=x²-{5x-[x²-6+6x]}
=x²-{5x-x²+6-6x}
=x²-{-x²+6-x}
=x²+x²-6+x
=2x²+x-6
2.已知（x+3)²+|y-1|=0可得
（x+3）²=0，y-1=0得x=-3，y=1
xy^2-2x^2y+[2xu^2-93xy^2-x^2y)] （看不懂）
3.x²y-[-x²y+(xyz-x²z)+xyz]-x²z
=x²y-[-x²y+xyz-x²z+xyz]-x²z
=x²y-[-x²y+2xyz+x²z]-x²z
=x²y+x²y-2xyz+x²z-x²z
=2x²y-2xyz
=2*(-1)²*(-2)-2*(-1)*(-2）*（1/3）
=-16/3
4.1/2x-(2x-2/3y²)+(-3/2x+1/3y²)
=1/2x-2x+2/3y²-3/2x-1/3y²
=-3x+1/3y²
=-3*(-1/3)+1/3*(-2)²
=7/3
1、x^2-{5x-[x^2-2(3-3x)]}
=x^2-{5x-[x^2-6+6x)]}
=x^2-{5x-x^2+6-6x}
=x^2+x+x^2-6
=2x^2-6
2、（x+3)^2>=0
|y-1|>=0
（x+3)^2+|y-1|=0
所以（x+3)^2=0,|y-1|=0
所以x=-3,y=1
xy^2-2x^2y+[2xu^2-93xy^2-x^2y)]
=-90xy^2-3x^2y
=-90