用数学归纳法证明与正整数n有关的命题P(n)时,证明的第二步中必须用上假设条件P(k)·但有些题目结构式子比较复杂,常常难以直接用上假设·本文给出设法变形,用上假设的若干处理方法·一、凑出假设例1求证n1+1+n1+2+…+21n=1-12+31-14+…+2n1-1-21n(n∈N*)·证明:(1)当n=1时,左 When the proposition P(n) related to positive integer n is proved by mathematical induction, the hypothesis P(k) must be used in the second step of the proof. However, some structural formulas are more complex and it is often difficult to use the hypothesis directly. Give a try to deform, using a number of methods of assumptions. I. Make a hypothesis Example 1 Prove n1+1+n1+2+...+21n=1-12+31-14+...+2n1-1-21n(n ∈N*) · Proof: (1) When n=1, left