1. The problem statement, all variables and given/known data How many continuous functions f are there which satisfy the equation (f(x)^2) = x^2 for all x? 2. Relevant equations 3. The attempt at a solution What method should I use to solve this? Is there a specific strategy involved besides plug and chug? Off the top of my head, I can only think of f(x)= x, but that's just one. Thank you.