Equivalencias asintóticas (infinitésimos)

Casos continuos: función de x, con u→0

sin⁡u∼u\sin u \sim usin⁡(3x)∼3x\sin(3x) \sim 3x
tan⁡u∼u\tan u \sim utan⁡(x2)∼x2\tan(x^{2}) \sim x^{2}
arcsin⁡u∼u\arcsin u \sim uarcsin⁡(2x)∼2x\arcsin(2x) \sim 2x
arctan⁡u∼u\arctan u \sim uarctan⁡ ⁣(x2)∼x2\arctan\!\left(\tfrac{x}{2}\right) \sim \tfrac{x}{2}
sinh⁡u∼u\sinh u \sim usinh⁡(4x)∼4x\sinh(4x) \sim 4x
1−cos⁡u∼u221-\cos u \sim \dfrac{u^{2}}{2}1−cos⁡(2x)∼2x21-\cos(2x) \sim 2x^{2}
eu−1∼ue^{u}-1 \sim ue3x−1∼3xe^{3x}-1 \sim 3x
au−1∼uln⁡a(a>0)a^{u}-1 \sim u\ln a \quad(a>0)2x−1∼xln⁡22^{x}-1 \sim x\ln 2
ln⁡(1+u)∼u\ln(1+u) \sim uln⁡(1+5x)∼5x\ln(1+5x) \sim 5x
(1+u)r−1∼r u(r≠0)(1+u)^{r}-1 \sim r\,u \quad(r\neq0)1+x−1∼x2\sqrt{1+x}-1 \sim \tfrac{x}{2}

Casos discretos: sucesión aₙ, con n→∞

sin⁡ ⁣(1n)∼1n\sin\!\left(\tfrac1n\right) \sim \tfrac1nnsin⁡ ⁣(1n)→1n\sin\!\left(\tfrac1n\right) \to 1
ln⁡ ⁣(1+1n)∼1n\ln\!\left(1+\tfrac1n\right) \sim \tfrac1nnln⁡ ⁣(1+1n)→1n\ln\!\left(1+\tfrac1n\right) \to 1
e1/n−1∼1ne^{1/n}-1 \sim \tfrac1nn(e1/n−1)→1n\left(e^{1/n}-1\right) \to 1
aknk+⋯+a0∼aknk(ak≠0)a_k n^{k} + \dots + a_0 \sim a_k n^{k} \quad(a_k\neq0)3n2+n2n2−5→32\dfrac{3n^{2}+n}{2n^{2}-5} \to \tfrac32
n!∼2πn(ne)n  (Stirling)n! \sim \sqrt{2\pi n}\left(\dfrac{n}{e}\right)^{n}\ \ \text{(Stirling)}n!nn→0\dfrac{n!}{n^{n}} \to 0