1 (1 x--2 y--2)^3的三重积分-搜答案-智慧作业帮

x=1/3y=1/2x-(x+y）+（x+2y)-(x+3y)+...-(x+13y)=6y-13y=-7y=-7/2=-3.5

2x-3y=0(1)3x-y-1=0(2)由（2）得y=3x-1(3)把y=3x-1代入(1)得2x-9x+3=0∴x=3/7把x=3/7代入（3）得y=2/7∴x=3/7y=2/7

(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)=4x^2-y^2+2xy-8x^2-y^2+4xy+2y^2-6xy=-4x^2=-4(-1/4)^2=-1/4

3x-4y/2x+y=1/26x-8y=2x+y4x=9yx/y=9/4

原试=-y-y-y.-y大概有50个-y所以答案是-50/3

1)x(x-y)(x+y)-x(x+y)^2=x((x-y)(x+y)-(x+y)^2)=x(x^2-y^2-x^2-2xy-y^2)=x(-2xy-2y^2)=-2xy(x+y)2)（2a+b)(2

解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy

=（x-(x+y)）+（(x+2y)-(x+3y)）+...+(（x+98y）-(x+99y)）=-y*50=2*50=100

7y(x-3y)²-2(3y-x)³=7y(x-3y)²+2(x-3y)³=(x-3y)²[7y+2(x-3y)=(x-3y)²(7y+2X

原式=(x-y)²-3(x-y)+1=3²-3×3+1x-y用3代替=1再问：3X+3Y是怎么转化成这个的3(X-Y)，什么理由再答：是-3x+3y不是3x+3y

画个图就出来了,自己动手,别都靠别人

第一项与第三项先合并9xy(x-y)(x+1)-3y(x-y)(3x+2y)+6y^2*(x-y)(x+1)=(x-y)(x+1)(9xy+6y^2)-3y(x-y)(3x+2y)=(x-y)(x+1

（-2x)(2x+1)=-2x×2x-2x×1=-4x²-2x(-3x+2y)(-3x-2y)=(-3x)²-(2y)²=9x²-4y²(-4x+3y

1.(2x-3y)^2-(y+3x)(3x-y)=4x^2-12xy+9y^2-(3x+y)(3x-y)=4x^2-12xy+9y^2-9x^2+y^2=10y^2-5x^2-12xy2.[(x-y)

把x=9y带入到3x=2y+1中得到3*(9y)=2y+127y=2y+125y=1y=1/25x=9y=9/25所以x=9/25,y=1/25

解3(x-1)-(x-5)=3x-3-x+5=(3x-x)+(5-3)=2x+22(x²-y²)-3(x²-2y²)=(2x²-3x²)+(

(x-2y)/(x+2y)=3取倒数(x+2y)/(x-2y)=1/3所以原式=(1/3)[(x-2y)/(x+2y)]-3[(x+2y)/(x-2y)]=(1/3)×3-3×(1/3)=0

【（x+2y）2-(x+y)(3x-y)-5y2】÷（2x）=[x^2+4xy+y^2-(3x^2+2xy-y^2)-5y^2]/(2x)=[-2x^2+2xy]/(2x)=y-x=1/2-2=-3/

-2x+3y=3x-2y+13y+2y=3x+2x+15y=5x+15y-5x=1y-x=1/5∴y＞x谢谢采纳满意请采纳