3x+3y=-3 x(x+y)(x+2y)=-8 求x,y3x+3y=-3 x(x+y)(x+2y)=8

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3x+3y=-3x(x+y)(x+2y)=-8求x,y3x+3y=-3x(x+y)(x+2y)=83x+3y=-3x(x+y)(x+2y)=-8求x,y3x+3y=-3x(x+y)(x+2y)=83x

3x+3y=-3 x(x+y)(x+2y)=-8 求x,y3x+3y=-3 x(x+y)(x+2y)=8
3x+3y=-3 x(x+y)(x+2y)=-8 求x,y
3x+3y=-3 x(x+y)(x+2y)=8

3x+3y=-3 x(x+y)(x+2y)=-8 求x,y3x+3y=-3 x(x+y)(x+2y)=8
∵ 3 x + 3 y = - 3
∴ x + y = - 1
∴ y = - 1 - x
∴ x(x + y)(x + 2 y)= 8 【把 y = - 1 - x 代入】
x(x - 1 - x)(x - 2 - 2 x)= 8
x ·(- 1)(- 2 - x)= 8
x(x + 2)= 8
x ² + 2 x = 8
x ² + 2 x + 1 = 9
(x + 1)²= 9
x + 1 = ± 3
x = ± 3 - 1
x1 = 3 - 1 = 2
x2 = - 3 - 1 = - 4
①当 x = 2 时,则 y = - 1 - 2 = - 3
② 当 x = - 4 时,则 y = - 1 -(- 4)= - 1 + 4 = 3

由3x+3y=-3得x+y= -1,即y= -1-x,
代入x(x+y)(x+2y)=8得 -x(-2-x)=8,即x²+2x-8=0,(x-2)(x+4)=0,
解得x=2,或x = -4,
x=2时,y= -3;x = -4时,y=3。

x=-4 y=3

∵3x+3y=-3
∴x+y=-1①
x(x+y)(x+2y)
=-x(x+2y)=-8
∴x(y+x+y)=x(y-1)=8
∴xy-x-8=0
将①代入得:x(-1-x)-x-8=0
∴x²-2x-8=0
∴(x-4)(x+2)=0
∴x=4或-2
∴x=4,y=-1-4=-5
或x=-2,y=-...

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∵3x+3y=-3
∴x+y=-1①
x(x+y)(x+2y)
=-x(x+2y)=-8
∴x(y+x+y)=x(y-1)=8
∴xy-x-8=0
将①代入得:x(-1-x)-x-8=0
∴x²-2x-8=0
∴(x-4)(x+2)=0
∴x=4或-2
∴x=4,y=-1-4=-5
或x=-2,y=-1-(-2)=1


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