log(10,000) = 4 = y
rewrite 10,000 in power base form. = 10000 = 10^4
apply the log rule,\( \log _a\left(x^b\right)=b\cdot \log _a\left(x\right)\)
\(\log _{10}\left(10^4\right)=4\log _{10}\left(10\right)\)
so, \(4\log _{10}\left(10\right)\)
apply the other log rule: \(\log _a\left(a\right)=1\)
\(\log _{10}\left(10\right)=1\)
= 1*4
= 4
log10 10000 = y
From the definition of logs:
Log10 x = y exactly if 10y = x
log10 10000 = y if 10y =10000 for 10y=10000 , y MUST = 4