a x ? 1 ~ x ln ? a a^x-1\sim x\ln a ax?1~xlna
log ? a ( 1 + x ) ~ x 1 ln ? a \log _a(1+x)\sim x\frac{1}{\ln a} loga?(1+x)~xlna1?
( log ? a x ) ′ = 1 x ln ? a (\log _ax)' =\frac{1}{x\ln a} (loga?x)′=xlna1?