己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,A-B的值

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己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,A-B的值
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己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,A-B的值
己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,
A-B的值

己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,A-B的值
A-B=(6x+4y-5)-(2(x+y)+(x-3))
=6x+4y-5-2x-2y-x+3
=3x+2y-2
=3×(-2)+2×(-2)-2
=(3+2+1)×(-2)
=6×(-2)
=-12

A-B=3x十2y-8=-20

A-B=6x+4y-5-【2(x+y)+(x-3)】
=6x+4y-5-2x-2y-x+3
=3x+2y-2
把x=y=-2带入
3x+2y-2
=3×(-2)+2×(-2)-2
=-6-4-2
=-12