Prove that loga(x)=logb(x)logb(a)\log_a(x) = \frac{\log_b(x)}{\log_b(a)}loga(x)=logb(a)logb(x) for any valid bases a,ba, ba,b and positive xxx.
False; the change of base formula involves subtraction, not division
True; this is the change of base formula derived from the definition of logarithm
Only true when a=ba = ba=b
True only for natural logarithm bases