如果是大题：x - 2y = 3① 2x + ky = 8 ②② - 2×① ===> (k+4)y = 2===> y = 2 / (k+4)③③代入①===> x = 3 + 2y =(3k+ 16) / (k+4) ④③、④代入 x+y=...