I have an equation lets say f(x). I derivate it then I need to find the equation of the tangent that touches f(x) at two different places.

> p:=x->log[b](x); p := x -> log[b](x) > o:=x->b^x; x o := x -> b > fsolve( p(x) = o(x) , {x,b} ); Error, (in fsolve) number of equations, 1, does not match number of variables, 2 I need to find the location (x,y) where they touch each other, thanks for the help.