f.1 maths

7(1-n)/4 = (5n+1)/2 + 0.4

7(1-n)/4 x 4 = (5n+1)/2 x 4 + 0.4 x 4

7(1-n) = 2(5n+1) + 1.6

7-7n = 10n + 2 + 1.6

10n + 2 + 1.6 = 7 - 7n

10n + 7n = 7 - 2 - 1.6

17n = 3.4

n = 3.4/17

=0.2

希望幫到你啦 !

2008-01-03 20:02:37 補充：
我自己係預科生 !

7(1-n)/4=(5n+1)/2+0.4
[7(1-n)/4]x4=[(5n+1)/2]x4+0.4x4
7(1-n)=2(5n+1)+1.6
7-7n=10n+2+1.6
7-2-1.6=10n+7n
3.4=17n
n=0.2

7(1-n)/4=(5n+1)/2+0.4
(7-7n)/4=(10n+2)+0.4
(7-7n)/4=10n+2+0.4
(7-7n)/4=10n+2.4
7-7n
------- =10n+2.4
4
7-7n=4(10n+2.4)
7-7n=40n+9.6
7-9.6=40n+7n
-2.6=47n
-2.6 47n
------ = -------
47 47
then就自己喇!!
mths要多做....