(a + b)(a - b) = 77,由于77只存在7 x 11与1x77两种情况,则可得四个方程组：1）a + b = 7a - b = 11解 a = 9,b = -22)a + b = 11a - b = 7a = 9,b =23)a + b = 1a - b = 77a = 39,b = -384)a + b = 77a - b = 1解 a ...