(2m+1)x+(m+1)y=7m+42mx+x+my+y=7m+4(2x+y-7)m=-x-y+4恒过某一定点就是与m无关则当2x+y-7=0且-x-y+4=0时等式恒成立此时与m无关2x+y-7=0-x-y+4=0所以x=3,y=1所以定点是(3,1)
