初中数学题库八年级6.8:两道含参二次根式的化简例题解析

初中数学题库八年级6.8:两道含参二次根式的化简例题解析

例题1、化简:\(\displaystyle \sqrt{{{{{\left( {x+2y} \right)}}^{2}}{{{\left( {x-y} \right)}}^{2}}}},\left( {0<x<y} \right)\)

原式\(\displaystyle =\left| {x+2y} \right|\times \left| {x-y} \right|\)

\(\displaystyle =\left( {x+2y} \right)\left( {y-x} \right)\)

\(\displaystyle =2{{y}^{2}}-2xy+xy-{{x}^{2}}\)

\(\displaystyle =2{{y}^{2}}-xy-{{x}^{2}}\)

例题2、化简:\(\displaystyle \sqrt{{125x{{y}^{2}}{{z}^{3}}\times 25x{{y}^{3}}{{z}^{2}}}}\)

原式\(\displaystyle =\sqrt{{125x{{y}^{2}}{{z}^{3}}}}\times \sqrt{{25x{{y}^{3}}{{z}^{2}}}}\)

\(\displaystyle =5yz\sqrt{{5xz}}\times 5yz\sqrt{{xy}}\)

\(\displaystyle =25xyz\sqrt{{5yz}}\)

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