請問第5條個答案,A同埋B既答案係咪可以調轉?
本帖最後由 Soldier 於 16-4-2009 21:28 編輯
請問有冇中文版，一打開先發現是英文。
其次第一題睇完呆左，做左成半個鍾先解到一半…囧rz
Rebellion.KLC 發表於 14-4-2009 23:07 http://www.nakuz.com/bbs/images/common/back.gif
佢只係轉左個樣咋,睇清楚d-.-呢題唔洗30秒都搞掂
1-6題既solution...(第7條...我而家先f4,未教probability....)
1.
(a+bc)(a-bc)/(b-ac)x(b-ac)^2/2(b-ac)
=(a^2-b^2c^2)/2
2.
6(x+2)>=7(x+2)(x-2)
(x+2)(20-7x)>=0
-2<=x<=20/7
3.a
x^3-3x^2+3x-1=0(binomial theorem=.=?)
(x-1)^3=0
x=1
b
from a
x^3-3x^2+3x-1=0
x^3-3x(x-1)-1=0
put x=y+17
(y+17)^3-3(y+17)(y+16)-1=0
(y+17-1)^3=0
y=-16
4.
QS^2=5^2+5^2
OP=OS=QS/2=√50/2
5.(煩...)
a+b+c=7---(1)
ab+ac+bc=0
ab+c(a+b)=0---(2)
abc=-36---(3)
from(3),
ab=-36/c---(4)
from(1),
c=7-a-b---(5)
a+b=7-c---(6)
sub(4)and(5)into(2)
-36/c+(7-a-b)(a+b)=0
-36/c+7(a+b)-(a+b)^2=0---(7)
sub(6)into(7)
-36/c+7(7-c)-(7-c)^2=0
c^3-7c+36=0
c=3
跟住自己ko埋佢
6.join AO and OC
let<OAB=a and <OCA=b
<OAB=<OBA=a
<OCA=<OCB=b
In tri ABC,
a+a+b+b+x+x=180
2(70)+2x=180
x=20
基本上頭6題10-15分鍾內KO
本帖最後由 【YU】 於 17-4-2009 00:27 編輯
32# Soldier
唔駛咁煩.....
a+b+c=7
a + b = 7 - c
sub in (2),
ab + bc + ca = 0
c(a+b) + ab = 0
multiply by c,
c^2(7-c)+abc = 0
c^2(7-c) - 36 = 0
c^3 - 7c^2 + 36 = 0
solved.
a,b,c = 3 , 6 , -2
FORM 4都識做
勁WOW
多謝樓上兩位整SOLUTION
34# hei2hk
form4野黎咋...當然識做...
份野唔太難...
不過唔多岩a(1)既程度喎...
相信a(2)又唔會出呢d
所以我覺得根本唔會咁出...
34# hei2hk
form4野黎咋...當然識做...
份野唔太難...
不過唔多岩a(1)既程度喎...
相信a(2)又唔會出呢d
所以我覺得根本唔會咁出...
xoscarhy12 發表於 18-4-2009 20:27 http://www1.nakuz.com/bbs/images/common/back.gif
呢份Mock都係睇你可以去到咩程度o者
呢份識既話 ,, Section 1 有咩可能唔識 ?
32# Soldier
唔駛咁煩.....
a+b+c=7
a + b = 7 - c
sub in (2),
ab + bc + ca = 0
c(a+b) + ab = 0
multiply by c,
c^2(7-c)+abc = 0
c^2(7-c) - 36 = 0
c^3 - 7c^2 + 36 = 0
solved.
a,b,c = 3 , 6 , -2 ...
【YU】 發表於 17-4-2009 00:26 http://www.nakuz.com/bbs/images/common/back.gif
c=3,6,-2
when c=3
b=6,a=-2
when c=6
b=-2,a=3
when c=-2
b=3,a=6
a,b,c 有好多ans下
2.
6(x+2)>=7(x+2)(x-2)
(x+2)(20-7x)>=0
-2<=x<=20/7
Soldier 發表於 16-4-2009 20:38 http://www.nakuz.com/bbs/images/common/back.gif
大過+等於ans唔係會-2<=x<=20/7
唔係應該係(x+2)(20-7x)=<0
大過+等於ans唔係會-2
kin~仔 發表於 18-4-2009 22:02 http://www.nakuz.com/bbs/images/common/back.gif
x^2既coe唔可以係負數,唔信可以用method of tabulation/graphical method double check個答案
姐係:
(x+2)(6-7(x-2))>=0
(x+2)(20-7x)>=0<----x^2既coe唔可以係負數,所以全式乘負
(x+2)(7x-20)<=0
..................
7)(A)
3/8*2/5*7/12+3/8*3/5*5/12+5/8*2/5*5/12
=137/480
(B) Expected?
137/480*1200+(1-137/480)*-100
=271.04166666....