(-3x^y+2xy)-( )=4x^+xy

问题描述:

(-3x^y+2xy)-( )=4x^+xy

(-3x^y+2xy)-(4x^+xy)
=-3x^y+2xy-4x^-xy
=-3x^y+xy-4x^
所以填上-3x^y+xy-4x^