x→0x\rightarrow 0x→0时
- x∼sinx∼tanx∼arcsinx∼arctanx∼ln(1+x)∼ex−1x\sim \sin x \sim \tan x \sim \arcsin x \sim \arctan x \sim \ln(1+x) \sim e^x-1x∼sinx∼tanx∼arcsinx∼arctanx∼ln(1+x)∼ex−1
- 1−cosx∼12x21−cosax∼a2x21-\cos x \sim \frac12x^2 \quad 1-\cos^a x \sim \frac a2 x^21−cosx∼21x21−cosax∼2ax2
- 1+x−1∼12x(1+x)a−1∼ax\sqrt{1+x}-1\sim \frac12x \quad (1+x)^a-1 \sim ax1+x−1∼21x(1+x)a−1∼ax