继前面两讲《公式求和》、《分组求和》之后，这里廖老师将介绍第三种数列求和方法：拆项消去求和。所谓“拆项消去求和”，是指把算式中的某一项或若干项拆分为两个数的和或两个数的差，然后达到相互抵消的目的，从而简化计算的过程，寻求到更简便的计算方法。

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