Question

Prove that if a, b, and c are real numbers, then la+b+cl<=lal+lbl+lcl

Answer 1

Can you do it with just two numbers, like |a+b| <= |a| + |b| ?

Answer 2

Would it be basically the same proof?

Answer 3

Exactly the same, yes.

Answer 4

Can you prove it?

Answer 5

Ok, yeah I have that one from an example in class.

Answer 6

Well then it's the same thing. Think of it like
|(a+b) + c| <= |(a+b)| + |c| <= |a| + |b| + |c|

Answer 7

Oh, that is super easy then, thanks