想問大家一條數,,
ab+bc-ac=0!|RWcp^3Ta-c=101i0f5ZwjV7` v/b`SR
求b'[^_`?D~-ww8e
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=0WH%{P bAt
b(101-c)+bc-c(101-c)=0
101c-bc+bc-101c+(c*c)=0
c*c=0
c=0
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a=101-0:V_+IK4TefkR
a=101
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ab+bc-ac=0
a=101p wG6o$M
c=0T8WBV}G9MaS9`+x
101b + 0*b - 101*0=0#v*ZHw&~:dg Z
101b=0
b=0 [quote]Originally posted by [i]ch.chak[/i] at 2008-1-17 09:38 PM:
a=101-cT+lH&Q`{s
ab+bc-ac=0&D!V fq%c9jH.a(@
b(101-c)+bc-c(101-c)=0
101c-bc+bc-101c+(c*c)=0m7r2kxm;o
c*c=0 z+rwXA$Z
c=0)d$ajaN
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a=101-0
a=101x7o H;}m}JH7j
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ab+bc-ac=0sx#d3ZI[&E
a=101
c=0
101b + 0*b - 101*0=0
101b=0
b=0 [/quote]
對不起nWc&aZ2l,X-K
請容許我指出錯誤*V&f^.d#t5AU
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在一開頭
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[color=Red]a=101-c[/color](原本是a-c=101,移項應該是a=101+c)
ab+bc-ac=0tI8v AUI$E_Pa
[color=Red]b[/color]([color=Red]101[/color]-c)+bc-c(101-c)=05F2|jx&Ye;u
[color=Red]101c[/color]-bc+bc-101c+(c*c)=0
c*c=0
c=04~P.H${+f`m
基於以上紅字的地方,其餘的地方我認為沒必要看了 [quote]Originally posted by [i]sakura310[/i] at 2008-1-17 09:58 PM:6|l~cjvK
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對不起
請容許我指出錯誤
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在... [/quote]&Iv]t{J)V}/nJ
係bo5s~M Z}3k
冇留意錯左tim [quote]Originally posted by [i]托迪仔T[/i] at 2008-1-17 07:42 PM:
a=101, b&c =0 :D [/quote].qX^PAz&^2i
ab+bc-ac=0 e)pd5})X]0y
a-c=101
求b4x(YWL2d8Up^
咁玩法...如果c係-101...a同b=0 都得架wo:D [quote]Originally posted by [i]sakura310[/i] at 09:58 PM: xXmY)Q'r\8d
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對不起4D8If@T%Y)j3QT8k,M
請容許我指出錯誤
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在... [/quote]
咁你又吾去計;);):P:P [quote]Originally posted by [i]playbr2[/i] at 2008-1-17 11:58 PM:*R.L"@vm8\7EW Z
咁你又吾去計;);):P:P [/quote]
playplay你串我?:mad::noway::fight::angry:(表情符號好好玩的說:D)N t,^ic|i p
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咁你呢~你又唔去計?:dev::dev:3b q|:UDy5`5vy
等了這麼久也沒人貼答案出來f.O nyzN)h
那麼讓小生物來獻醜了:redface::redface::redface:]3[W6@G6iz1z
手寫關係,所以上傳圖片先了(懶得去打)
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由於題目沒有說到a,b和c是甚麼數,我暫且假設係整數黎做(光是實數的話...太沒意思了...)
如果是實數的話,那麼請看到左邊2/3就可以了,中間和右邊是整數的解集(次序:左>中>右)
用的不是甚麼古怪的方法,應該好易睇得明4GNh ]w
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這算一種對付三個未知數,但只有兩式的求整數解方法
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有不明的話可以提出f5[*{1b$WYS'V
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不過我要訓醒頭覺先回覆到,好累的說(脫力中...)
[[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])z6|6F)I Y'Jfa
乜咁快手ㄚㄚㄚㄚ:D:D:D:D#A j ?*F p3`
個答案可以咁.....)TW2_1o8La^
1.ab+bc-ac=0Wj&T3H.BV:^8I:{
a-c=101;vk]0zU
b=ac/(a+c)=(101c+c^2)/(101+2c)_oO!dcI` u
設c=101n
101n代入c
[101^2*n+(101n)^2]/(101+202n)3|)ZF"[:buu
=[(101^2)n(n+1)]/[(101)(2n+1)]7Ja Y kEVi/B|
=[101n(n+1)]/(2n+1),Q0k%{1b#kn
因為a、b、c是正整數
所以n是正整數'Z oy+{O!tD'WoF|
所以[101n(n+1)]/(2n+1)是整數[tkJ{1i2];o
2n+1=101(剩下的2n+1=n或2n+1=n+1,n沒有整數解)
n=50
a=5151 <--a-c=101
b=2550 <--[101n(n+1)]/(2n+1)
c=5050 <--c=101nF&lOY$c*j:?"M(N
答案:b=2550 Filename: DSC01158.JPG
Datetime | Downloaded by | Counts,G$Z%F1GQ!GcU
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 | 2
點解大家都down兩次? XD [quote]Originally posted by [i]sakura310[/i] at 12:27 AM:ag6`|'G!\
Filename: DSC01158.JPGm*h7}O^lFrs
Datetime | Downloaded by | Counts cm'y e/x6o2|)\
2008-01-18 00:25:24 | 阿感 | 2
2008-01-18 00:24:20 | playbr2 | 2pV(ae-]H
2008-01-18 00:22:02 | 但丁 | 2o N jx+Ba"o~?
點解大家都down兩次? XD [/quote]
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我第一次開睇左2秒就close 左:P:PVj8j*OL|za
之後DL (就变成第二次) [quote]Originally posted by [i]sakura310[/i] at 12:27 AM:
Filename: DSC01158.JPG
Datetime | Downloaded by | Counts4m.DA*xa2m%h$`
2008-01-18 00:25:24 | 阿感 | 2:Ar9k/J[j
2008-01-18 00:24:20 | playbr2 | 2
2008-01-18 00:22:02 | 但丁 | 28U5O/d7J\m
$Mv*SQb b j/IlD
點解大家都down兩次? XD [/quote]
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快d捉我錯處:D:D:D3v#M/Dw"StT7U
話吾定我都打錯 + - 符號
係電腦打答案...的確幾煩...又哂時間...:giveup: 捉錯處就唔敢當
不過,c=101n哥度(解除n係正整數的限制,只是整數):v:A)v'b,v
就一下子限制左c一定要係101的倍數(好像看懸疑片,突然劇情說出一些事前沒提及過的線索,不爽~)&KJg!IHJ-t(CU
知道{101,0,0}和{5151,2550,5050}係答案的話,當然沒問題!g8]8YGB)q
但原先是不知答案,所以唔知有無失根
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有時見到題目都感到有點不爽3Ur6l!_7]KxA
題目所求的答案是整數,正整數,有理數,實數等等應該說清楚
有些題目,整數解和正整數解分別好大的說,要找出整數解集有時可不是件易事= = 冇答案ga....-N%w DEE5V_`4o
2條equation solve 唔到3個unknown ga.... [quote]Originally posted by [i]cutec[/i] at 2008-1-18 08:26 AM:
冇答案ga....2k n)b5c:|cD
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2條equation solve 唔到3個unknown ga.... [/quote](Ub B/r&Ta4l
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agree
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2 equations 2 unknows
if 3 unknows there should be 3 equations
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make it simple 6pj+G1e5L fep f
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say i N;|(AWY5u
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a + b +c = 3
a+b = 2@x#g,C-Wj&_
5]3A LM(t~C*b
then c is 1 RM ewnX5xX
a = 2 - b
so 0 = 0 }?1w:zA
:giveup: [quote]Originally posted by [i]cutec[/i] at 2008-1-18 08:26 AM:FDnc"p$m
冇答案ga....2|!m/Eo2E$]G
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2條equation solve 唔到3個unknown ga.... [/quote]