1/(x-7)+1/(x-12)=1/(x-6)+1/(x-11)
问题描述：
1/(x-7)+1/(x-12)=1/(x-6)+1/(x-11)
x=9是成立吗
答
把x = 9 代入方程1/(x-7)+1/(x-12)=1/(x-6)+1/(x-11)
左边＝1/2 + 1/-3 = 1/2 - 1/3 = 1/6
右边＝1/3 + 1/-2 = 1/3 - 1/2 = - 1/6
左边≠右边
所以 x = 9不能使方程成立反了，是1/(x-7)+1/(x-11)=1/(x-6)+1/(x-12)你也真是把x＝9先代入左边，再代入右边，比较一下两边上否相等就行了。左边＝1/(9-7) + 1/(9-11) = 1/2 - 1/2 =0右边＝1/(9-6) + 1/(9-12)= 1/3 - 1/3 = 0所以，x = 9能使方程成立