推 zxcv0011 :算幾? 11/08 00:05
推 yasfun :|x+1/x| = |x|+|1/x| if x不為0且x為實數 11/08 00:17
|x+1/x| = |x|+|1/x| >= 2
|x+1/x| + 4 >= 6
故 6 > a , a 屬於 (-∞,6)
※ 編輯: lilygarfield 來自: 111.243.164.211 (11/08 00:29)
→ theoculus :同乘x=> xy = x^2 + 1 => x^2 - yx + 1 = 0 =>判別式 11/08 00:28