求值:4x²y-[6xy-2(4xy-2)-x²y]+1,其中x=-1/2

问题描述:

求值:4x²y-[6xy-2(4xy-2)-x²y]+1,其中x=-1/2

把X=1/2带进去算不就行了么 原式=1/4y-3 对吗?????

化简
原式=4x^2y-[6xy-8xy+4-x^2y]+1
=5x^2y+2xy-3
y不知道,反正就这样代指进入

x=-1/2
4x²y-[6xy-2(4xy-2)-x²y]+1
=5x²y-6xy+2(4xy-2)+1
=5x²y+2xy-3
=5/4y-y-3
=y/4-3