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从近几年的中考试题来看,经常出现一类规律型的试题.本文以2013年的中考题为例,略作剖析以供参考.1.单项式的规律型试题.(2013年淮安)观察一列单项式:1x,3x2,5x2,7x,9x2,11x2,…,则第2013个单项式是.分析本题考查单项式的知识,解答本题关键是先看系数的变化规律,然后看x的指数的变化规律,从而确定第2013个单项式.解系数依次为1,3,5,7,9,11,…2n-1:x的指数依次是1,2,2,1,2,2,1,2,2,可见三个单项式一个循环,故可得第2013个单项式的系数为4025;∵20133=671,∴第2013个单项式指数为2,故可得第BAA
From the examination questions in recent years, there are often a regular type of test questions.This paper takes the 2013 test questions as an example, a little analysis for reference .1. The first one is the monad type: 1x, 3x2, 5x2, 7x, 9x2, 11x2, ..., then the 2013th monomial is. Analyze the knowledge of this essay to examine the monomials, the key to answering this question is to look at the changing law of the coefficients first, , So as to determine the 2013th monomial solution.The coefficient of solution is 1, 3, 5, 7, 9, 11, ... 2n-1: The index of x is 1,2,2,1,2,2,1,2, 2, we can see that there are three cycles of the three monomials. Therefore, the coefficient of the 2013 monomial is 4025, ∵20133 = 671, and the index of the 2013 monomial is 2. Therefore,