Here's the question you clicked on:
littlemiss
4^x=12
\[b^x=A\iff x=\frac{\ln(A)}{\ln(b)}\]
this is sometimes called the "change of base" formula in your case \(A=12,b=4\)
Log both sides so u get log 4^x =log 12. therefore by law of logs x log 4 = log 12. so x=log 12/log 4...
\[\log 4^{x} = \log 12\] \[x \log 4 = \log 12 \] \[x = \log 12\div \log 4 \]