HEeeeeYY

Bring armor with very high def best you can get. Use a Thunder weapon Devil Slicer or True Devil Slicer will be good enough. Watch out for when it charges because it turns. Use traps to your advantage and hit it's head to try and end it quickly. If you are having trouble killing still why not try capturing them so you wont have to keep fighting till they're dead. Capturing creatures also equals better reawards but no carves. If the quest requires you to slay the TigerX then just disregard the capturing suggestion. The weakest part is the head, the second weakest part is near it's neck, third is it's back, and everywhere else will do the least damage.

Ive defeated it using a
Complete tigrex armor
With earplug and autotracker
You must lock on to
A single tigrex first
Use flash bombs
And thunder weapons are
Great like the true devil slicer
Or kirin thundersword
First cut it's tail off
It somehow slows it a bit
Use traps and capturing it is much easier
Because it somehow take long to kill it.
After you kill one it's easy to
Concentrate in killing
The 2nd one.
Do the same method!
Flash bombs are the key!