Demarre and Alaysha are trying to decide where the graph of $f(x)=\frac{1}{x^2}$ is concave up and where it is concave down. They both agree that it is concave up for $x<0$, but Alaysha says that it can not be concave up for $x>0$ since the function is decreasing. Demarre says that it does not matter; all that matters is that it curves up. Who is correct? Explain your answer.