Question: is log x log base 10?
Answer: The base-10, or "common", log is popular for historical reasons, and is usually written as "log(x)". ... If a log has no base written, you should generally (in algebra classes) assume that the base is 10. The other important log is the "natural", or base-e, log, denoted as "ln(x)" and usually pronounced as "ell-enn-of-x".