1. The problem statement, all variables and given/known data 1] l x + y l < or equal to l x l + l y l 2. Relevant equations x^2 + 2xy + y^2 3. The attempt at a solution Left side. i Squared left side to begin with, and i got x^2 + 2xy + y^2 and also did the same for the right side, but it would have absolute sign between each variable. x^2 + 2xy + y^2 < or equal to lxl^2 + 2lxllyl + lyl^2 so its just (x + y)^2 < or equal to ( lxl+lyl )^2 not sure what im supppose to do next.. it just seems like im doing somethign and undoing something without any purpose. can anyone clear this from my head?