非應屆生，防雷
單選 (3) / (5) / (4)
多選 (3)(5) / (1)(4) / (2)(5) / (1)(4) / (2)(4)
選填 9,-2 / 2,6,-3 / 15
非選 1. (1)π/72 (2)60度 (3)6:22
2. (1)略 (2)-1/8 (3) (1/5)^(2n+1) + (1/5)^(2n+2) - (1/3)^(2n+1)
= (1/5)^(2n+1) * (6/5) - (1/3)^(2n+1)
= (1/5)^(2n) * (6/25) - (1/3)^(2n) * (1/3) < 0
(1/5 < 1/3 且 6/25 < 1/3)
利用遞減數列跟 0、-1/8分別是上下界可說明不等式恆成立