-(x平方y+3xy-4)+3(x平方y-xy-2)

问题描述:

-(x平方y+3xy-4)+3(x平方y-xy-2)

-(x平方y+3xy-4)+3(x平方y-xy-2)
=-x²-3xy+4+3x²y-3xy-6
=-x²-6xy+3x²y-2
=