Find the value of x where the function is discontinuous.

f (x) = x^3+3^x

A (x) = x^3 is a polynomial function, and polynomial functions are continuous for all x,

b (x) = 3^x is an exponential function, continuous for all x.

f (x) = a (x) + b (x) is continuous because the sum of 2 continuous functions is a continuous function.

Answer: f is continuous for all x in the real numbers