计算18(4x²-xy)-19(4x²-xy)+(4x²-xy-1),

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计算18(4x²-xy)-19(4x²-xy)+(4x²-xy-1),
计算18(4x²-xy)-19(4x²-xy)+(4x²-xy-1),

计算18(4x²-xy)-19(4x²-xy)+(4x²-xy-1),
18(4x²-xy)-19(4x²-xy)+(4x²-xy-1)
=72x²-18xy-76x²+19xy+4x²-xy-1
=-4x²+xy+4x²-xy-1
=-1

18(4x²-xy)-19(4x²-xy)+(4x²-xy-1)
=-(4x²-xy)+(4x²-xy)-1
=-1