form2既主項變換.

1.試以x表示y.
1-x/x = n+y/y
xn+xy=y-xy
xn+2xy=y
x(x+2y)=y
x=y/(x+2y)



2.試以y表示x.
n+y/y = 1-x/x
y-xy=xn+xy
y(1-x-x)=xn
y=xn/(1-2x)

1.
1-x/x = n+y/y
(1-x)/x = (n+y)/y
y(1-x) = x(n+y)
y-xy = xn+xy
y = xn+xy+xy
y = xn+2xy
y=x(n+2y)
x = y / (n+2y)

2.
n+y/y = 1-x/x
(n+y)/y = (1-x)/x
x(n+y) = y(1-x)
xn+xy = y-xy
xn = y-xy-xy
xn = y-2xy
xn = y(1-2x)
y = (xn) / (1-2x)



2010-11-17 23:49:56 補充：
OH NO.....

我把兩題答案倒轉左.....

吾=>"我"的意思
吾識做=>"我"識做..
咁仲黎問乜

1.
(1-x)/x = (n+y)/y
y(1-x) = (n+y)x
y-xy=nx+xy
y-2xy = nx
y(1-2x)=nx
y=nx/(1-2x)

2.
(1-x)/x = (n+y)/y
y(1-x) = (n+y)x
y-xy=nx+xy
y=nx+2xy
y=x(n+2y)
x=y/(n+2y)