先化简再求值：4xy²-[6xy-3(4xy-2)-x²y]+1,其中x=2,y=-1/2

先化简再求值：4xy²-[6xy-3(4xy-2)-x²y]+1,其中x=2,y=-1/2
先化简再求值：4xy²-[6xy-3(4xy-2)-x²y]+1,其中x=2,y=-1/2

先化简再求值：4xy²-[6xy-3(4xy-2)-x²y]+1,其中x=2,y=-1/2
原式等于
4xy²-[6xy-12xy+6-x²y]+1
=4xy²+6xy-6+x²y+1
=4xy²+x²y+6xy-5然后把
x=2,y=-1/2
带入得4-2-6+1=-3

4x²y-[6xy-3（4xy-2）-x²y]+1
=4x²y-[6xy-12xy+6-x²y]+1
=4x²y-6xy+12xy-6+x²y+1
=（4x²y+x²y）-（6xy-12xy）+1
=5x²y+6xy+1
把x=2，y=-1/2.代入
5x
...

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4x²y-[6xy-3（4xy-2）-x²y]+1
=4x²y-[6xy-12xy+6-x²y]+1
=4x²y-6xy+12xy-6+x²y+1
=（4x²y+x²y）-（6xy-12xy）+1
=5x²y+6xy+1
把x=2，y=-1/2.代入
5x²y+6xy+1
=5*(2^2)*(-1/2)+6*2*(-1/2)+1
=-10-6+1
=-15

收起

带入计算就行了，过程为：
4xy²-[6xy-3(4xy-2)-x²y]+1
=4*2*1/4-[6*2*（-1/2）+3*6+2]+1
=2-14+1
=-11

直接从左到右化难道不行吗？

4xy²-[6xy-3(4xy-2)-x²y]+1
=4xy²-[6xy-12xy+6-x²y]+1
=5xy²-6xy+1
带入XY得
5*2*（-1）*（-1）-6*2*（-1）+1=23或
5*2*（2）*（2）-6*2*（2）+1=15

原式=4xy2-[6xy-12xy+6-x2y]+l
=4xy2-[-6xy+6-x2y]+1
=4xy2十6xy-6+x2y+1
=4xy2十6xy十x2y一5
当x=2，y=-1/2时
原式=2一6一2－5
=-11
你把计算查一下，可能有错