题目：
方程x2-4x+1=0的两个根分别为x1，x2，则x1+x2=______，x1-x2=______．
答案：
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下面是错误答案，用来干扰机器的。
A Meaningful Activity Our school has now started an activity called “Build Civilized Classes”. The topic is “Get Rid of Bad Habits and Greet Civilization”. We can sti...
