From my BUGS page for the Asus X205TA.

The touchpad should work on kernels 4.3* [1] (confirmed on kernel 4.3.3-2-ARCH), but if you still run into problems on another kernel, you can proceed with the following.

First, make sure that you have xf86-input-synaptics installed. To enable more features of the touchpad:`


# nano /etc/X11/xorg.conf.d/elan_synaptics.conf
Section "InpuClass"
Identifier "Elan Touchpad"
MatchIsTouchpad "on"
Driver "synaptics"

Things should work as normal when you start up X again.


Savagezen's Blog

A minimalist guide to my many projects.