当 (f(x) ightarrow 0) 时，有：
[egin{align}
sin f(x) &acksim f(x)
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an f(x) &acksim f(x)
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ln (1+f(x)) &acksim f(x)
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e^{f(x)} - 1 &acksim f(x)
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arcsin f(x) &acksim f(x)
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arctan f(x) &acksim f(x)
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log_a (1+f(x)) &acksim cfrac{f(x)}{ln a}
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a^{f(x)} - 1 &acksim f(x) ln a
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1-cos f(x) &acksim cfrac{1}{2} f^2(x)
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ln(f(x)+sqrt{1+f^2(x)}) &acksim f(x)
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f(x) - sin f(x) &acksim cfrac{1}{6} f^3(x)
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an f(x) - f(x) &acksim cfrac{1}{3} f^3(x)
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(1 + f(x))^ alpha - 1 &acksim alpha f(x)
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arcsin f(x) - f(x) &acksim cfrac{1}{6} f^3(x)
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f(x) - arctan f(x) &acksim cfrac{1}{3} f^3(x)
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an f(x) - sin f(x) &acksim cfrac{1}{2} f^3(x)
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end{align}
]