Write the Word or Phrase That Best Completes Each Statement $$\text { A function defined by } y = a b ^ { x } \text { can be written in terms of an exponential function base } e \text { as }$$

Write the word or phrase that best completes each statement or answers the question.
Provide the missing information.
- $$\text { A function defined by } y = a b ^ { x } \text { can be written in terms of an exponential function base } e \text { as }$$ ________