y = （2x+3） / (x-1)
= (2x - 2 + 5 ) / (x-1)
= 2 + 5/(x-1)
y-2 = 5 /(x-1)
x-1 = 5 / (y-2)
x = 1 + 5/ (y-2)
所以 反函数为 y = 1+ 5/ (x-2)