How do you prove that the curves of y=xx and y = the Functional Continued Fraction (FCF) generated by y=xx(1+1y) touch y=x, at their common point ( 1, 1 )?

1 Answer
Aug 27, 2016

The curves intersect without osculating.

Explanation:

Considering

y=xx(1+1y)yyy+1xx we have

f1(x,y)=yyy+1xx=0 and
f2(x,y)=yxx=0

Those functions intersect at clearly at {x=1,y=1}. This can be verified by simple substitution.

Now the tangency at this point obeys

(dydx)1=(f1)x(f1)y=(1+y)2(1+loge(x))1+y+loge(y)=2
(dydx)2=(f2)x(f2)y=xx(1+loge(x))=1

So they intersect without osculating.