Prove that ordinal arithmetic is associative

[cragar]

Homework Statement

Let a, b, c be ordinals.
Prove that a+(b+c)=(a+b)+c

Homework Equations

The Attempt at a Solution

I looked at a set theory book by Jech and he says Prove by induction on c.
Should I look at the case where its true for c+1[/B]

 

[micromass]

Come on. There's no single thing you could attempt here??
What is transfinite induction? What do you need to do for it?