(1)
y=lg x/(x+1)
x/(x+1)=10^y
x=(x+1) * 10^y
x(1-10^y)=10^y
x=10^y/(1-10^y)
(2)
y= (e^x-1)/(e^x+1)
(e^x-1)=y*(e^x+1)
e^x -1 = ye^x + y
e^x(1-y) = y + 1
e^x = (1+y)/(1-y)
x = ln((1+y)/(1-y))
(完)