常言道“小技巧,办大事”,取一个数(式)的倒数,就是这样一个能“办大事”、解难题的小技巧.1分子有理化“取倒数”对于分子有理化,有关键作用,进而可化简根式、比较大小、判断函数单调性等.例1求值log(2-1)(3+22).解log(2-1)(3+22)=log(2-1)(2+1)2=log(2-1)21-12=-2.例2已知c1 As the saying goes, “tips and tricks” and the reciprocal of a number are just such a trick to “solve major problems.” 1 The rationalization of molecules “taking the reciprocal” has a key role in the rationalization of molecules , Which in turn can be simplified root, size, determine the monotonicity of the function, etc. Example 1 Evaluation log (2-1) (3 +22) Solution log (2-1) (3 + 22) = log ) (2 + 1) 2 = log (2-1) 21-12 = -2 Example 2 Known c1