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| 2017/06/17 00:29:17瀏覽39｜回應0｜推薦0 | |
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此文章來自奇摩知識+如有不便請留言告知 f.2maths 開方要step 急~! help !!發問: 1. 3√8 - √50 2. 2√5over3 + √60 3. √15 * √6 4.3√7 * 2√14 5. 4√21 / √3 6. √14 / 2√28 最佳解答: 1. 3√8 - √50 =3×2√2-5√2 =6√2-5√2 =√2 2. 2√(5/3)+√60 =2√5/√3+2√15 =2√5/√3×(√3/√3)+2√15 =2√(5×3)/3+2√15 =2√15/3+2√15 令a=2√15 2√15/3+2√15 =a/3+a =a/3+a^2/a =a^2/3a+3a^2/3a =(a^2+3a^2)/3a =4a^2/3a =4a/3 a=2√15 =8√15/3 3. √15×√6 =√(15×6) =√90 =3√10 4. 3√7×2√14 =6√(7×14) =6√(7×7×2) =6×7√2 =42√2 5. 4√21/√3 =4√(21/3) =4√7 6. √14/2√28 =(1/2)(√(14/28)) =(1/2)(√(1/2)) =(1/2)×1/√2 =(1/2)×√2/2 =√2/4 其他解答: |
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