已知單項式3amb2與−23a4bn-1的和是單項式,那麼-m+n=______.

已知單項式3amb2與−23a4bn-1的和是單項式,那麼-m+n=______.

由題意得,3amb2與−23a4bn-1是同類項,∴m=4,n-1=2,解得:m=4,n=3,∴-m+n=-1.故答案為:-1.