Problem 14. Let f:R2→R be defined by setting f(0)=0 and f(x,y)=x2+y2xy if (x,y)=0. 1. For which vectors u=0 does f′(0
Posted: Wed Jul 13, 2022 5:08 am
Problem 14. Let f:R2→R be defined by setting f(0)=0 and f(x,y)=x2+y2xy if (x,y)=0. 1. For which vectors u=0 does f′(0;u) exist? Evaluate it when it exists. 2. Do D1f and D2f exist at 0 ? 3. Is f differentiable at 0 ? 4. Is f continuous at 0 ?