For "find where f is not differentiable":

1. Find all corner points (absolute value expressions change sign)
2. Find all cusp points (fractional power functions at zero)
3. Find all vertical tangent points (like x^(1/3) at 0)
4. Check piecewise function junction points
5. Check where floor/ceiling functions have jumps

For "find parameters for differentiability":

1. Set LHL = RHL = f(a) (continuity equation)
2. Set left derivative = right derivative (differentiability equation)
3. Solve the system

For "is f differentiable at a?":

1. First check continuity (necessary condition)
2. If continuous, compute f'(a) using the limit definition
3. Do NOT rely on computing lim f'(x) — this can fail (x^2 sin(1/x) example)