✔ 最佳答案
圖片參考:
http://i1096.photobucket.com/albums/g340/pingshek/2012-03-29-1.png
http://i1096.photobucket.com/albums/g340/pingshek/2012-03-29-1.png
2012-03-30 01:55:36 補充:
忘了一項其本技巧:
無論是正數或負數,其偶數次方都必是是正數。例如 (±1)² = |±1|² = 1
所以 a^6 = (a)^6,b^12 = |b|^12,c^16 = |c|^16,b^6 = |b|^6
但奇數次方卻保留其正負號。例如 (1)³ = 1 而 (-1)³ = -1
所以 a^3 和 c^9 都分別保留 a 和 c 的原來正負數。
2012-03-30 01:56:28 補充:
(a^8 x b^12 x c^16)^(1/4) / (a^3 x b^6 x c^9)^(1/3)
= (|a|^8 x |b|^12 x |c|^16)^(1/4) / (a^3 x |b|^6 x c^9)^(1/3)
= [|a|^(8/4) x |b|^(12/4) x |c|^(16/4)] / [a^(3/3) x |b|^(6/3) x c^(9/3)]
2012-03-30 01:56:43 補充:
= [|a|^2 x |b|^3 x |c|^4)] / [a x |b|^2 x c^3]
= (|a|^2)/a x (|b|^3)/(|b|^2) x (|c|^4)/c^3
= a^(2-1) x |b|^(3-2) x c^(4-3)
= a x |b| x c ...... (答案)