Seznam základních limit

Obecně

lim h 0 f ( x + h ) f ( x ) h = f ( x ) {\displaystyle \lim _{h\to 0}{f(x+h)-f(x) \over h}=f'(x)} (definice derivace)
lim x c f ( x ) g ( x ) = lim x c f ( x ) g ( x ) ,  pokud je  lim x c f ( x ) = lim x c g ( x ) = 0  nebo  ± {\displaystyle \lim _{x\to c}{\frac {f(x)}{g(x)}}=\lim _{x\to c}{\frac {f'(x)}{g'(x)}},\qquad {\text{ pokud je }}\lim _{x\to c}f(x)=\lim _{x\to c}g(x)=0{\text{ nebo }}\pm \infty } (L'Hospitalovo pravidlo)
lim h 0 ( f ( x + h ) f ( x ) ) 1 h = exp ( f ( x ) f ( x ) ) {\displaystyle \lim _{h\to 0}\left({\frac {f(x+h)}{f(x)}}\right)^{\frac {1}{h}}=\exp \left({\frac {f'(x)}{f(x)}}\right)}
lim h 0 ( f ( x ( 1 + h ) ) f ( x ) ) 1 h = exp ( x f ( x ) f ( x ) ) {\displaystyle \lim _{h\to 0}{\left({f(x(1+h)) \over {f(x)}}\right)^{1 \over {h}}}=\exp \left({\frac {xf'(x)}{f(x)}}\right)}

Vlastnosti limit funkcí

Pokud  lim x c f ( x ) = L 1 R  a  lim x c g ( x ) = L 2 R  pak: {\displaystyle {\text{Pokud }}\lim _{x\to c}f(x)=L_{1}\in \mathbb {R} {\text{ a }}\lim _{x\to c}g(x)=L_{2}\in \mathbb {R} {\text{ pak:}}}
lim x c [ f ( x ) ± g ( x ) ] = L 1 ± L 2 {\displaystyle \lim _{x\to c}\,[f(x)\pm g(x)]=L_{1}\pm L_{2}}
lim x c [ f ( x ) g ( x ) ] = L 1 × L 2 {\displaystyle \lim _{x\to c}\,[f(x)g(x)]=L_{1}\times L_{2}}
lim x c f ( x ) g ( x ) = L 1 L 2 ,  když  L 2 0 {\displaystyle \lim _{x\to c}{\frac {f(x)}{g(x)}}={\frac {L_{1}}{L_{2}}},\qquad {\text{ když }}L_{2}\neq 0}
lim x c f ( x ) n = L 1 n ,  pokud je  n  z množiny Z + {\displaystyle \lim _{x\to c}\,f(x)^{n}=L_{1}^{n},\qquad {\text{ pokud je }}n{\text{ z množiny Z}}^{+}}
lim x c f ( x ) 1 n = L 1 1 n ,  pokud  n  je kladné liché, nebo pokud je sudé a zároveň  L 1 > 0 {\displaystyle \lim _{x\to c}\,f(x)^{1 \over n}=L_{1}^{1 \over n},\qquad {\text{ pokud }}n{\text{ je kladné liché, nebo pokud je sudé a zároveň }}L_{1}>0}

Základní funkce

lim x c a = a {\displaystyle \lim _{x\to c}a=a}
lim x c x = c {\displaystyle \lim _{x\to c}x=c}
lim x c a x + b = a c + b {\displaystyle \lim _{x\to c}ax+b=ac+b}
lim x c x r = c r  Pokud je  r  kladné celé číslo  {\displaystyle \lim _{x\to c}x^{r}=c^{r}\qquad {\mbox{ Pokud je }}r{\mbox{ kladné celé číslo }}}
lim x 0 + 1 x r = + {\displaystyle \lim _{x\to 0^{+}}{\frac {1}{x^{r}}}=+\infty }
lim x 0 1 x r = { , pokud je  r  liché + , pokud je  r  sudé {\displaystyle \lim _{x\to 0^{-}}{\frac {1}{x^{r}}}={\begin{cases}-\infty ,&{\text{pokud je }}r{\text{ liché}}\\+\infty ,&{\text{pokud je }}r{\text{ sudé}}\end{cases}}}

Logaritmické a exponenciální funkce

lim x 1 ln ( x ) x 1 = 1 {\displaystyle \lim _{x\to 1}{\frac {\ln(x)}{x-1}}=1}

nebo

lim y 0 ln ( y + 1 ) y = 1 {\displaystyle \lim _{y\to 0}{\frac {\ln(y+1)}{y}}=1}
Když  a > 1 : {\displaystyle {\mbox{Když }}a>1:\,}
lim x 0 + log a x = {\displaystyle \lim _{x\to 0^{+}}\log _{a}x=-\infty }
lim x log a x = {\displaystyle \lim _{x\to \infty }\log _{a}x=\infty }
lim x a x = 0 {\displaystyle \lim _{x\to -\infty }a^{x}=0}
Když  a < 1 : {\displaystyle {\mbox{Když }}a<1:\,}
lim x a x = {\displaystyle \lim _{x\to -\infty }a^{x}=\infty }

Trigonometrické funkce

lim x a sin x = sin a {\displaystyle \lim _{x\to a}\sin x=\sin a}
lim x a cos x = cos a {\displaystyle \lim _{x\to a}\cos x=\cos a}
lim x 0 sin x x = 1 {\displaystyle \lim _{x\to 0}{\frac {\sin x}{x}}=1}
lim x 0 1 cos x x = 0 {\displaystyle \lim _{x\to 0}{\frac {1-\cos x}{x}}=0}
lim x 0 1 cos x x 2 = 1 2 {\displaystyle \lim _{x\to 0}{\frac {1-\cos x}{x^{2}}}={\frac {1}{2}}}
lim x n ± tan ( π x + π 2 ) = Pro každé celé  n {\displaystyle \lim _{x\to n^{\pm }}\tan \left(\pi x+{\frac {\pi }{2}}\right)=\mp \infty \qquad {\text{Pro každé celé }}n}
lim x 0 sin a x x = a {\displaystyle \lim _{x\to 0}{\frac {\sin ax}{x}}=a}
lim x 0 sin a x b x = a b {\displaystyle \lim _{x\to 0}{\frac {\sin ax}{bx}}={\frac {a}{b}}}

Speciální limity

lim x + ( 1 + k x ) m x = e m k {\displaystyle \lim _{x\to +\infty }\left(1+{\frac {k}{x}}\right)^{mx}=e^{mk}}
lim x + ( 1 + 1 x ) x = e {\displaystyle \lim _{x\to +\infty }\left(1+{\frac {1}{x}}\right)^{x}=e}
lim x + ( 1 1 x ) x = 1 e {\displaystyle \lim _{x\to +\infty }\left(1-{\frac {1}{x}}\right)^{x}={\frac {1}{e}}}
lim x + ( 1 + k x ) x = e k {\displaystyle \lim _{x\to +\infty }\left(1+{\frac {k}{x}}\right)^{x}=e^{k}}
lim n n n ! n = e {\displaystyle \lim _{n\to \infty }{\frac {n}{\sqrt[{n}]{n!}}}=e}
lim n 2 n 2 2 + 2 + ... + 2 n = π {\displaystyle \lim _{n\to \infty }\,2^{n}\underbrace {\sqrt {2-{\sqrt {2+{\sqrt {2+{\text{...}}+{\sqrt {2}}}}}}}} _{n}=\pi }
lim x 0 ( a x 1 x ) = ln a ,   a > 0 {\displaystyle \lim _{x\to 0}\left({\frac {a^{x}-1}{x}}\right)=\ln {a},\qquad \forall ~a>0}

Limity poblíž nekonečna

lim x N / x = 0  pro všechna reálná  N {\displaystyle \lim _{x\to \infty }N/x=0{\text{ pro všechna reálná }}N}
lim x x / N = { , N > 0 nedefinováno , N = 0 , N < 0 {\displaystyle \lim _{x\to \infty }x/N={\begin{cases}\infty ,&N>0\\{\text{nedefinováno}},&N=0\\-\infty ,&N<0\end{cases}}}
lim x x N = { , N > 0 1 , N = 0 0 , N < 0 {\displaystyle \lim _{x\to \infty }x^{N}={\begin{cases}\infty ,&N>0\\1,&N=0\\0,&N<0\end{cases}}}
lim x N x = { , N > 1 1 , N = 1 0 , 0 < N < 1 {\displaystyle \lim _{x\to \infty }N^{x}={\begin{cases}\infty ,&N>1\\1,&N=1\\0,&0<N<1\end{cases}}}
lim x N x = lim x 1 / N x = 0  pro každé  N > 1 {\displaystyle \lim _{x\to \infty }N^{-x}=\lim _{x\to \infty }1/N^{x}=0{\text{ pro každé }}N>1}
lim x N x = { 1 , N > 0 0 , N = 0 nedefinováno v R , N < 0 {\displaystyle \lim _{x\to \infty }{\sqrt[{x}]{N}}={\begin{cases}1,&N>0\\0,&N=0\\{\text{nedefinováno v R}},&N<0\end{cases}}}
lim x x N =  pro každé  N > 0 {\displaystyle \lim _{x\to \infty }{\sqrt[{N}]{x}}=\infty {\text{ pro každé }}N>0}
lim x log x = {\displaystyle \lim _{x\to \infty }\log x=\infty }
lim x 0 + log x = {\displaystyle \lim _{x\to 0^{+}}\log x=-\infty }

Literatura

  • BARTSCH, Hans-Jochen. Matematické vzorce. 4. vyd. Praha: Academia, 1994. 832 s. ISBN 80-200-1448-9.