※ 引述《royalray (火紅眼)》之銘言：
: 國中生問的題目,離國中太遠了,都忘光了!可以幫幫我嗎??
: 題目在照片中,共兩題,麻煩大家了
: http://imgur.com/a/6XPdT
: 麻煩大家幫我解解!!
1.
K = 1/1991 + 2/1992 + ... + 1/2000
=> 10* 1/2000 < K < 10* 1/1991
=> 1991/10 < 1/K < 2000/10
=> 1/K = 199.xxxxxxxxx
2.
(b-a) / ab = 1/1998
=> ab + 1998a - 1998b =0
=> (a-1998)(b+1998) = -1998^2 = - (2^2 * 3^6 * 37^2)
-1898 ≦ a-1998 ≦ -999
2098 ≦ b+1998 ≦ 2997
a-1998│ -1332 │ -1369
───┼─────┼─────
b+1998│ 2997 │ 2916
───┼─────┼─────
a │ 666 │ 629
───┼─────┼─────
b │ 999 │ 918
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迷途中唯一的導航 是對自己誠實
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※ 編輯: Tiderus (123.240.91.95), 12/14/2015 23:20:44