笔者认为《数学通报》1988年第5期发表的“注重习题教学发展学生思维能力”一文例1中证法四利用数学归纳法证明恒等式C_n~1+2C_n~2+3C_n~3+…+nC_n~n=n·2~(n-1)的过程是错误的。过程中k+1型结论的正确性,根本未用到k型结论正确性的假设,违背了数学归纳法的证明原则,正确证明应为 The author believes that the “mathematical bulletin” published in the fifth issue of 1988, “focus on problem-solving teaching to develop students’ thinking ability” in a case 1 Chinese proficiency test four using mathematical induction to prove the identity of C_n~1+2C_n~2+3C_n~3+...+nC_n The process of ~n=n·2~(n-1) is wrong. The correctness of the k+1 type of conclusions in the process does not use the assumption of the correctness of the k-form conclusion at all, contrary to the proof principle of mathematical induction, and the correct proof should be