maths~~!
2008-07-10 6:06 pm
回答 (1)
2008-07-10 6:52 pm
✔ 最佳答案
cuberoot( 20 + 14 sqrt2 ) + cuberoot( 20 – 14 sqrt2 )= cuberoot[ 2^3 + 3(2)^2(sqrt2) + 3(2)(sqrt2)^2 + (sqrt2)^3 ]
+ cuberoot[ 2^3 – 3(2)^2(sqrt2) + 3(2)(sqrt2)^2 – (sqrt2)^3 ]
= cuberoot( 2 + sqrt2 )^3 + cuberoot( 2 – sqrt2 )^3
= ( 2 + sqrt2 ) + ( 2 – sqrt2 )
= 4
參考: knowledge
收錄日期: 2021-04-23 20:36:00
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080710000051KK00588