The x-axis serves as a horizontal asymptote for all exponential functions. Exponential functions are of the form f(x) = ax . The domain consists of all real numbers. However, the range only consists of all numbers greater than zero. This is because no matter how large x gets, the graph will shoot upwards towards infinity. If x becomes a negative, we know that we will get f(x) = 1/a2 . The larger the negative number, the closer the function approaches zero. So, for exponential functions we will always have that restriction that the range will only include positive numbers. I hope this answers your question. I believe the statement is true.
