Hello, 1. The problem statement, all variables and given/known data I was asked to prove that for every x>=0, ln(1+x)>=(x-x^2/2). 2. Relevant equations 3. The attempt at a solution I defined f(x) thus: f(x) = ln(1+x) + x^2/2 - x and found f'(x)=x^2/(1+x). I hence wrote that since f'(x) is always non-negative for every x>=0 (since x^2>=0 in that domain) f(x) is likewise always positive. Does that suffice?