回複：請幫忙，一道數學題

來源: 於 2010-09-05 19:41:51 [舊帖] [給我悄悄話] 本文已被閱讀：次

(x+1/x)^2=9, ==>
x^2+1/x^2=7
(x^2+1/x^2)^2=49==>
x^4+1/x^4 = 47