Rage and Expertise

[Jaxom]

Under Barbarian class it states that when a Barbarbarian rages they can't perform a task that requires concentration.
It also states that a barabrian can't use Expertise while raging, does this also effect the Improved Trip and Knock Down feats since thier prerequisite is Expertise (for Improved Trip) and Improved Trip (for Knock Down).

 

[Caliban]

Under Barbarian class it states that when a Barbarbarian rages they can't perform a task that requires concentration.
It also states that a barabrian can't use Expertise while raging, does this also effect the Improved Trip and Knock Down feats since thier prerequisite is Expertise (for Improved Trip) and Improved Trip (for Knock Down).

No, they can still use Improved Trip and Knockdown. They still have the Expertise feat, they just can't use it.