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高中数学必修 第一册(648题)


求下列各式的值:


\(\sqrt {\frac {3-2\sqrt {2}} {3+2\sqrt {2}}}\);   




知识点:第四章 指数函数与对数函数


参考答案:法一:\(\sqrt {\frac {3-2\sqrt {2}} {3+2\sqrt {2}}}=\sqrt {\frac {\left ( {\sqrt {2}-1} \right )^{2}} {\left ( {\sqrt {2}+1} \right )^{2}}}=\frac {\sqrt {2}-1} {\sqrt {2}+1}=\frac {\left ( {\sqrt {2}-1} \right )^{2}} {\left ( {\sqrt {2}+1} \right )\left ( {\sqrt {2}-1} \right )}=3-2\sqrt {2}\)

法二:\(\sqrt {\frac {3-2\sqrt {2}} {3+2\sqrt {2}}}=\sqrt {\frac {\left ( {3-2\sqrt {2}} \right )^{2}} {\left ( {3+2\sqrt {2}} \right )\left ( {3-2\sqrt {2}} \right )}}=3-2\sqrt {2}\)

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