數學!!!急~~

主項變換 (change of subject)
　　　x + 2
y = ———　　　　　[x]
　　　2 - x

y(2 - x) = x+2
2y - xy = x+2
2y - 2 = x + xy
2y - 2 = x(1+ y)
2y - 2 / 1+ y = x
x = 2y - 2 / 1+ y

ans :　　　　2y - 2
　　　　x = _______
　　　　　　　y+1

y(2-x)=x+2
2y-xy=x+2
2y-2=x+xy
2y-2=x(1+y)

2y-2
____=x
1+y

2y-2
x =____
y+1
=Ans
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y = (x+2) / (2-x)

y(2-x) = x+2

2y-xy=x+2

2y-2=x+xy

2y-2=x(1+y)

(2y-2)/(1+y)=x

Therefore,

x= (2y-2) / (y+1)

y(2-x) = x+2
___ (2-x)
2-x


2y-xy = x+2
2y-2 = x + xy
2y-2 = x(y+1)

2y-2 = x(y+1)
___ _____
y+1 y+1

x = 2y -2
_____
y+1



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