We need to find the equation of a tangent line, and to do that you need to find derivative to be able to complete the equation.
So, it gives y= (x-1)/(x-2) on coordinate (3,2)
I say:
a=3
f(a)=2
f`(3)= ?
Using lim h-->0 f(a+h)-f(a) / h to find f`(3)
I plug in [(3+h-1)/(3+h-2) -2] / h
=(3+h-1)-2(3+h-2) / h(3+h-2) (After multiplying by CD)
=3+h-1-6-2h+4 / 3h+h^2-2h
=-2 / 2h+h-2
=-2/-2
=1
The book is showing the derivative as -1. Where did I mess up here?