这是〔1〕上国内外习题精选中的一道题,原解法是依据条件(1)巧妙地用 c+a、-(a+b)分别去代换-b、c,从而使未知元减少一个,未知元虽说减少一个,计算过程还是冗繁,为此,〔2〕又介绍了一种方法,它进而利用条件(1)的齐次性,将未知元减少为一个,于是计算过程相对地易于进行.但是,欲证的等式(2) This is a problem in the [1] home and abroad exercise selection, the original solution is based on the conditions (1) skillfully use c + a, - (a + b) to substitute - b, c, respectively, so that the unknown To reduce one, although the unknown element is reduced by one, the calculation process is still tedious. Therefore, [2] introduces a method that further uses the homogeneity of condition (1) to reduce the unknown element to one, so the calculation process is relatively Easy to carry out. However, the equation to be proved (2)