想問大家一條數,,
ab+bc-ac=0a-c=101
求b
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要STEPS,,,THX a=101, b&c =0 :D 我都知,,但唔知點得出個ans.,,anyway,,THX a=101-c
ab+bc-ac=0
b(101-c)+bc-c(101-c)=0.k4C5K {P"M4|
101c-bc+bc-101c+(c*c)=0$y&E1J1O0r sr
c*c=04Z*~e Uh%{Q a ^
c=0:aXu-UN;Zk7{
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a=101-0
a=101
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ab+bc-ac=0 N QT;{[i^G
a=101
c=0 s*Kf'n$V3Vm^0c
101b + 0*b - 101*0=0
101b=0&Q'd r(B-aN\#c#v N
b=0 [quote]Originally posted by [i]ch.chak[/i] at 2008-1-17 09:38 PM:
a=101-c
ab+bc-ac=09p8q&F{ bG_
b(101-c)+bc-c(101-c)=0:` ` qQ I x
101c-bc+bc-101c+(c*c)=0
c*c=0} j0U C5O K9l
c=0od_xE3]1E
a=101-0
a=101
ab+bc-ac=0
a=101
c=0
101b + 0*b - 101*0=0]0X^8X t3T
101b=0
b=0 [/quote]l!^ ]0o^1I ?
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對不起 ^r;A j!l
請容許我指出錯誤
在一開頭.COxV$pV V ]4h/{2|
[color=Red]a=101-c[/color](原本是a-c=101,移項應該是a=101+c)'Uj O ih/y6q6y!{
ab+bc-ac=0
[color=Red]b[/color]([color=Red]101[/color]-c)+bc-c(101-c)=0
[color=Red]101c[/color]-bc+bc-101c+(c*c)=0
c*c=0
c=0
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基於以上紅字的地方,其餘的地方我認為沒必要看了 [quote]Originally posted by [i]sakura310[/i] at 2008-1-17 09:58 PM:
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對不起
請容許我指出錯誤4u%{*q-C_)m F
在... [/quote] `3Z k? j6f&j6rz
係bo
冇留意錯左tim [quote]Originally posted by [i]托迪仔T[/i] at 2008-1-17 07:42 PM:
a=101, b&c =0 :D [/quote]U'\_ we
ab+bc-ac=0 Ti B C;jc
a-c=1016by|P} A\bQl
求b
咁玩法...如果c係-101...a同b=0 都得架wo:D [quote]Originally posted by [i]sakura310[/i] at 09:58 PM: }DS s Ht v4K
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對不起
請容許我指出錯誤
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在... [/quote]8V;vq6~ OV#d"] bS
咁你又吾去計;);):P:P [quote]Originally posted by [i]playbr2[/i] at 2008-1-17 11:58 PM:B @2p)Qp
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咁你又吾去計;);):P:P [/quote]
playplay你串我?:mad::noway::fight::angry:(表情符號好好玩的說:D)
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咁你呢~你又唔去計?:dev::dev:7t"@3l&t,mC1_p
等了這麼久也沒人貼答案出來
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那麼讓小生物來獻醜了:redface::redface::redface:yC C }*X]
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手寫關係,所以上傳圖片先了(懶得去打)
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由於題目沒有說到a,b和c是甚麼數,我暫且假設係整數黎做(光是實數的話...太沒意思了...)
如果是實數的話,那麼請看到左邊2/3就可以了,中間和右邊是整數的解集(次序:左>中>右)
用的不是甚麼古怪的方法,應該好易睇得明
這算一種對付三個未知數,但只有兩式的求整數解方法7CLi S)L%p7} KU _
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有不明的話可以提出ZO4N5Z {L
不過我要訓醒頭覺先回覆到,好累的說(脫力中...)
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[[i] Last edited by sakura310 on 2008-1-18 at 12:12 AM [/i]] [quote]Originally posted by [i]sakura310[/i] at 12:08 AM:
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playplay你串我?:mad::noway::fig... [/quote] Peq*^W#K
乜咁快手ㄚㄚㄚㄚ:D:D:D:D0p%`k&F h B#l U ]
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個答案可以咁.....
1.ab+bc-ac=0
a-c=101
b=ac/(a+c)=(101c+c^2)/(101+2c)4s#a M? X:T+?
設c=101nU[^r0S ~ F
101n代入c
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[101^2*n+(101n)^2]/(101+202n);o)R5z:`YY
=[(101^2)n(n+1)]/[(101)(2n+1)]
=[101n(n+1)]/(2n+1)
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因為a、b、c是正整數
所以n是正整數
所以[101n(n+1)]/(2n+1)是整數
2n+1=101(剩下的2n+1=n或2n+1=n+1，n沒有整數解)Fu ^7DQz
n=505Cy J2f2R`R
a=5151 <--a-c=101
b=2550 <--[101n(n+1)]/(2n+1);|5d,MK~`
c=5050 <--c=101n/} Y)d%? HW!Hv uR
答案:b=2550 Filename: DSC01158.JPG
Datetime | Downloaded by | Counts
2008-01-18 00:25:24 | 阿感 | 28~fX,{ zp)zp
2008-01-18 00:24:20 | playbr2 | 2 Q,bul!E-O q'b%S
2008-01-18 00:22:02 | 但丁 | 2
點解大家都down兩次? XD [quote]Originally posted by [i]sakura310[/i] at 12:27 AM:
Filename: DSC01158.JPG.|-w9}1W;Z6bm
Datetime | Downloaded by | Counts
2008-01-18 00:25:24 | 阿感 | 2
2008-01-18 00:24:20 | playbr2 | 2,wO#i!T9Yf4\;j X
2008-01-18 00:22:02 | 但丁 | 25|)z0Xcgi7V
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點解大家都down兩次? XD [/quote]
我第一次開睇左2秒就close 左:P:P6RK|}/OG"cx
之後DL (就变成第二次) [quote]Originally posted by [i]sakura310[/i] at 12:27 AM:{?lWX h}[&L7e+g
Filename: DSC01158.JPG
Datetime | Downloaded by | Counts
2008-01-18 00:25:24 | 阿感 | 2
2008-01-18 00:24:20 | playbr2 | 2
2008-01-18 00:22:02 | 但丁 | 2Y2dh+C D Ul kA
點解大家都down兩次? XD [/quote]$h:V d;Tf/r1I%D
快d捉我錯處:D:D:DU,n$~-CR
話吾定我都打錯 + - 符號
係電腦打答案...的確幾煩...又哂時間...:giveup: 捉錯處就唔敢當
不過,c=101n哥度(解除n係正整數的限制,只是整數)cd,F$x)[x.M R X
就一下子限制左c一定要係101的倍數(好像看懸疑片,突然劇情說出一些事前沒提及過的線索,不爽~) jVg's$L9c@
知道{101,0,0}和{5151,2550,5050}係答案的話,當然沒問題
但原先是不知答案,所以唔知有無失根
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有時見到題目都感到有點不爽
題目所求的答案是整數,正整數,有理數,實數等等應該說清楚2wC&FB5G gUZ
有些題目,整數解和正整數解分別好大的說,要找出整數解集有時可不是件易事= = 冇答案ga....0B4GI)sK;ej9\
2條equation solve 唔到3個unknown ga.... [quote]Originally posted by [i]cutec[/i] at 2008-1-18 08:26 AM:
冇答案ga....*jO]!X Om
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2條equation solve 唔到3個unknown ga.... [/quote]7Z!Jc*G U*YK W0JN
agree )C,CZa M%h-S P:e F
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2 equations 2 unknows
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if 3 unknows there should be 3 equations 4f L YS Ir ]^!}
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make it simple dT R;?6i Y-B/\
say
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a + b +c = 3\7h8bI V9E k#g'q
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a+b = 2
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then c is 1 2OR8?%c wX
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a = 2 - b l.V M0\]
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so 0 = 0
:giveup: [quote]Originally posted by [i]cutec[/i] at 2008-1-18 08:26 AM:O X?'kp%DL
冇答案ga....
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2條equation solve 唔到3個unknown ga.... [/quote] e9rk)_*g'C
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此言差矣~-X ]x j {-]
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2條equation solve 唔到3個unknown ga
還欠一個條件,就是3條equation都是linear independent(線性無關)的
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簡單點說,多元一次方程就是線性方程的一個例子
在這情況下,當然是想求n個未知數,至少要用n條線性無關的方程5l\1^\ b9N%W
如果不是線性的話,有機會1條方程解3個未知數的(這不是每次都可以的啦~)
例如 x^2-2(x+8y)+17+4y^2+z^0.5=0 就只有唯一整數解
有興趣就解解看:sleep:6Hm;m qz0b^7T v
不懂的話就問playplay,佢會知答案:dev: [quote]Originally posted by [i]sakura310[/i] at 10:22 AM: ?e.S A8d%j?1ZL
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不懂的話就問playplay,佢會知答案[/quote]
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:cry::giveup::giveup::giveup::giveup: [quote]Originally posted by [i]sakura310[/i] at 06:47 AM:L$H@*I1u8h0O
捉錯處就唔敢當
不過,c=101n哥度(解... [/quote]
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都係睇餸食飯姐 , 無理由因為題目冇同你假設就下下大包圍架
反而適當地調節一下 , 咁會理性好多H F5Sbv0G Y l
就好似隻game 由12粒珠 加到13粒珠咁
當''堂''好玩哂:P:P:Pl5r qD v5e
p.s. 求''堂''字正寫:agree::giveup: **** 作者被禁止或刪除 內容自動屏蔽 ****
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