1題 F.1數,急!!!入黎la

Let a be the number of chicken and
let b be the number of rabbit with four legs and
let c be the number of rabbit with three legs.
a+b+c=35

2a+4b+3c=90

(c/b+c)=1/3

3x(c/b+c)=(1/3)x3

3c/(b+c)=1

(b+c)x3c/(b+c)=1x(b+c)

3c=b+c

2c=b

a+b+c=35

a+2c+c=35

a+3c=35

a=(35-3c)

2a+4b+3c=90

2(35-3c)+4(2c)+3c=90

(70-6c)+8c+3c=90

5c=90-70

c=4
The number of rabbit with three legs is 4.
The number of rabbit with four legs

=b

=2c

=8

The number of chicken

=35-b-c

=35-8-4

=23

Therefore, The number of rabbit with four legs is 8 and the number of chicken
is 23.

這是f.1奧數吧= =
好難...
anyway,

let雞數be C
let兔數be R

/ C R=35......(i)
\ 2C 1/3*3R 2/3*4R=90......(ii)
From (i),
R=35-C......(iii)

Put(iii)into(ii),
2C 1/3(3)(35-C) 2/3(4)(35-C)=90
2C 35-C 8/3(35)-8/3(C)=90
6C 105-3C 280-8C=270
-5C=-115
C=23

.'. 雞數=23, 4腳兔數=(35-23)2/3=8

(驗算)
雞數=23
4腳兔數=8
3腳兔數=4
頭數=23 8 4=35(對了)
腳數=2(23) 4(8) 3(4)=90(對了)

算對了~~~

2008-10-11 22:53:57 補充：
聲明

我無抄litkkn
我開始打字時佢都未post個ans出來