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2007年9月,我接手北师大版《数学》七年级上册的教学.在很短的一段时间里,在课堂上,我竟两次遭遇了“老师,为什么1+2+22+23+…+2n-1=2n-1?”这个问题.
In September 2007, I took over Beijing Normal University’s seventh grade mathematics teaching. In a very short period of time, in the classroom, I actually encountered the teacher twice. Why 1+2+22+23? +...+2n-1=2n-1?"This question.