  Let $B$ be an one-point extension of a finite dimensional $k$-algebra $A$ by
a simple $A$-module at a source point $i$. In this paper, we classify the
$\tau$-tilting modules over $B$. Moreover, it is shown that there are equations
  $$|\tilt B|=|\tilt A|+|\tilt A/\langle e_i\rangle|\quad \text{and}\quad
|\stilt B|=2|\stilt A|+|\stilt A/\langle e_i\rangle|.$$
  As a consequence, we can calculate the numbers of $\tau$-tilting modules and
support $\tau$-tilting modules over linearly Dynkin type algebras whose square
radical are zero.
