To determine the concavity of a function \( f(x) \) given the equation of the second derivative, follow these steps:
1. Compute the second derivative of \( f(x) \) if it's not already given.
2. Set up the second derivative equal to zero and solve for \( x \). These points are potential inflection points where the concavity might change.
3. Pick test points within intervals determined by the critical points found in step 2.
4. Plug these test points into the second derivative.
5. Determine the sign of the second derivative at each test point:
- If the second derivative is positive, the function is concave up in that interval.
- If the second derivative is negative, the function is concave down in that interval.
6. Based on the signs of the second derivative in each interval, determine the concavity of the function over its entire domain.
Remember that an inflection point doesn't always guarantee a change in concavity. It's possible for a function to have inflection points where the concavity remains the same.