MATHS (因式分解)

(50/x)*x + 0.2x - 50/x*5 - 0.2*5 = 54 首先展開

50 + 0.2x - 250/x - 1=54

0.2x - 250/x +49 -54=0 計哂d常數

0.2x - 250/x - 5 =0 全條式乘x

0.2x(square) - 5x -250 =0 全條式乘5 ，咁就無左個0.2

x(suare) - 25x -1250 =0 因式分解

(x-50) (x+25) =0

x=50 or x=-25

x=-25 or 50

Ans is x = -100 or x = 125

2006-12-21 23:00:30 補充：
SORRY THE CORRECT ANS IS(50/x+0.2)(x-5)=54(X-50)x(X+25)=0so X=50 or X=-25

(50/x+0.2)(x-5)=54
(50x/x)+0.2x-5(50/x)-5(0.2)=54
50+0.2x-250/x-1=54
0.2x-250/x=54+1-50
0.2x^2-5x-250=0
x=50or-25

2006-12-21 22:22:02 補充：
put x=50 into (50/x 0.2)(x-5)L.H.S.=(50/50 0.2)(50-5)=(1 0.2)(45)=54=R.H.S.L.H.S.=(50/-25 0.2)(-25-5)=(-2 0.2)(-30)=54=R.H.S.

(50/x+0.2)(x-5)=54

50/x+0.2=54/x-5

50x-250=54x+108

-4x=358

x= -89.5

我都好耐冇計maths, 唔知係咪咁

(50/x+0.2)(x-5)=54
=50/x+1/5=-54/5
50/x=-55/5(=-11)
50/x=-11
x=-11/50

very easy!!