先化简,再求值:4x的二次方y-【6xy-2(4xy-2)-x的二次方y】+1,其中x=-二分之一,y=1(要过程)
问题描述:
先化简,再求值:4x的二次方y-【6xy-2(4xy-2)-x的二次方y】+1,其中x=-二分之一,y=1(要过程)
答
4x²y-[6xy-2(4xy-2)-x²y]+1
=4x²y-(6xy-8xy+4-x²y)+1
=5x²y+2xy-3
=xy(5x+2)-3
=0.5(5×0.5+2)-3
=0.75
答
4x²y-【6xy-2(4xy-2)-x²y】+1
=4x²y-6xy+8xy+4+x²y+1
=5x²y+2xy+5
=5*(-0.5)² *1+2*(-0.5)*1+5
=2.75