Logarithmic type: f(xy) = f(x) + f(y) for x,y > 0 implies f(x) = k*ln(x). Setting x = y = 1: f(1) = 0. If f(e) = 1, then f = ln. If f(a) = 1, then f = $log_a$. Additive (Cauchy) type: f(x+y) = f(x) + f(y) implies f(x) = cx with continuity. Setting x = y = 0: f(0) = 0. Setting y = -x: f(-x) = -f(x). In JEE, these are usually 1-2 mark MCQs: identify the function type from the equation, use given values to find constants, evaluate at the required point. Power type: f(xy) = f(x)*f(y) implies f(x) = $x^n$.