(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Prove that

|x+y|^{2}+ |x-y|^{2}= 2|x|^{2}+ 2|y|^{2}

ifxandyare elements of ℝ^{k}

2. Relevant equations

Ordinary stuff

3. The attempt at a solution

Got the first part, but I don't understand the parallelogram thing yet. The little sketch I drew didn't help.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Interpret this geometrically, as a statement about parallelograms.

**Physics Forums | Science Articles, Homework Help, Discussion**