Question

学习分式一章后,老师出了这样一道方程问题(1/X-7)-(1/X-5)=(1/X-6)(1/X-4),小明按照去分母的方

Answer 1

（1）(1/X - a) (1/x - b) = (1/x - c) (1/x - d)

1/x^2 - 1/x (a + b) + ab = 1/x^2 - 1/x (c + d) + cd

-> (a + b - c - d) 1/x = ab - cd

把a = b + c - d代入 -> 2 (b - d) 1/x = (b + c - d) b - cd =

b^2 + bc - bd - cd = b (b - d) + c (b - d) = (b + c) (b - d)

两边约分得 1/x = (b + c)/2 = (a + b + c + d)/4

这是第一小题.