1. The problem statement, all variables and given/known data Find dy/dx and d^y/dx^2 x=e^t; y=te^(-t) For which values of t are concave upward? (write your answer in interval notation). 2. Relevant equations 3. The attempt at a solution I used the formula to find d^2y/dx^2. d^2y/dx^2= e^(-3t)*(2t-3) Set it to zero: e^(3t)*(2t-3)>0 I solved it and got t>3/2, but the computer told me it was wrong. What am I doing wrong here?