4x的平方y-[6xy-3(4xy-2)-x的平方y]+1,其中x=2,y=2分之1

问题描述:

4x的平方y-[6xy-3(4xy-2)-x的平方y]+1,其中x=2,y=2分之1

先化简,再求值!
4x²y-[6xy-3(4xy-2)-x²y]+1
=4x²y-(6xy-12xy+6-x²y)+1
=5x²y+6xy-5
=xy(5x+6)-5
因为x=2,y=2分之1,所以:
4x²y-[6xy-3(4xy-2)-x²y]+1
=2*2分之1*(5*2+6)-5
=16-5
=11