若3x+y+1=0,则代数式3(3x-y)-2(x-y)+9-x+3y=

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若3x+y+1=0,则代数式3(3x-y)-2(x-y)+9-x+3y=

3(3x-y)-2(x-y)+9-x+3y
=9x-3y-2x+2y+9-x+3y
=6x+2y+9
=6x+2y+2+7
=3(3x+2y+1)+7
=3x0+7
=7


3x+y+1=0
3x+y=-1
3(3x-y)-2(x-y)+9-x+3y
=9x-3y-2x+2y+9-x+3y
=(9x-2x-x)+(-3y+2y+3y)+9
=6x+2y+9
=2(3x+y)+9
=2×(-1)+9
=-2+9
=7

∵3x+y+1=0
∴3x+y=-1
3(3x-y)-2(x-y)+9-x+3y
=9x-3y-2x+2y+9-x+3y
=6x+2y+9
=2(3x+y)+9
=2×(-1)+9
=-2+9
=7