Andra derivatan av $$$\sin{\left(2 x \right)}$$$
Relaterade kalkylatorer: Derivata-beräknare, Kalkylator för logaritmisk derivering
Din inmatning
Bestäm $$$\frac{d^{2}}{dx^{2}} \left(\sin{\left(2 x \right)}\right)$$$.
Lösning
Bestäm den första derivatan $$$\frac{d}{dx} \left(\sin{\left(2 x \right)}\right)$$$
Funktionen $$$\sin{\left(2 x \right)}$$$ är sammansättningen $$$f{\left(g{\left(x \right)} \right)}$$$ av två funktioner $$$f{\left(u \right)} = \sin{\left(u \right)}$$$ och $$$g{\left(x \right)} = 2 x$$$.
Tillämpa kedjeregeln $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:
$${\color{red}\left(\frac{d}{dx} \left(\sin{\left(2 x \right)}\right)\right)} = {\color{red}\left(\frac{d}{du} \left(\sin{\left(u \right)}\right) \frac{d}{dx} \left(2 x\right)\right)}$$Derivatan av sinus är $$$\frac{d}{du} \left(\sin{\left(u \right)}\right) = \cos{\left(u \right)}$$$:
$${\color{red}\left(\frac{d}{du} \left(\sin{\left(u \right)}\right)\right)} \frac{d}{dx} \left(2 x\right) = {\color{red}\left(\cos{\left(u \right)}\right)} \frac{d}{dx} \left(2 x\right)$$Återgå till den ursprungliga variabeln:
$$\cos{\left({\color{red}\left(u\right)} \right)} \frac{d}{dx} \left(2 x\right) = \cos{\left({\color{red}\left(2 x\right)} \right)} \frac{d}{dx} \left(2 x\right)$$Tillämpa konstantfaktorregeln $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ med $$$c = 2$$$ och $$$f{\left(x \right)} = x$$$:
$$\cos{\left(2 x \right)} {\color{red}\left(\frac{d}{dx} \left(2 x\right)\right)} = \cos{\left(2 x \right)} {\color{red}\left(2 \frac{d}{dx} \left(x\right)\right)}$$Tillämpa potensregeln $$$\frac{d}{dx} \left(x^{n}\right) = n x^{n - 1}$$$ med $$$n = 1$$$, det vill säga $$$\frac{d}{dx} \left(x\right) = 1$$$:
$$2 \cos{\left(2 x \right)} {\color{red}\left(\frac{d}{dx} \left(x\right)\right)} = 2 \cos{\left(2 x \right)} {\color{red}\left(1\right)}$$Alltså, $$$\frac{d}{dx} \left(\sin{\left(2 x \right)}\right) = 2 \cos{\left(2 x \right)}$$$.
Därefter, $$$\frac{d^{2}}{dx^{2}} \left(\sin{\left(2 x \right)}\right) = \frac{d}{dx} \left(2 \cos{\left(2 x \right)}\right)$$$
Tillämpa konstantfaktorregeln $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ med $$$c = 2$$$ och $$$f{\left(x \right)} = \cos{\left(2 x \right)}$$$:
$${\color{red}\left(\frac{d}{dx} \left(2 \cos{\left(2 x \right)}\right)\right)} = {\color{red}\left(2 \frac{d}{dx} \left(\cos{\left(2 x \right)}\right)\right)}$$Funktionen $$$\cos{\left(2 x \right)}$$$ är sammansättningen $$$f{\left(g{\left(x \right)} \right)}$$$ av två funktioner $$$f{\left(u \right)} = \cos{\left(u \right)}$$$ och $$$g{\left(x \right)} = 2 x$$$.
Tillämpa kedjeregeln $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:
$$2 {\color{red}\left(\frac{d}{dx} \left(\cos{\left(2 x \right)}\right)\right)} = 2 {\color{red}\left(\frac{d}{du} \left(\cos{\left(u \right)}\right) \frac{d}{dx} \left(2 x\right)\right)}$$Derivatan av cosinus är $$$\frac{d}{du} \left(\cos{\left(u \right)}\right) = - \sin{\left(u \right)}$$$:
$$2 {\color{red}\left(\frac{d}{du} \left(\cos{\left(u \right)}\right)\right)} \frac{d}{dx} \left(2 x\right) = 2 {\color{red}\left(- \sin{\left(u \right)}\right)} \frac{d}{dx} \left(2 x\right)$$Återgå till den ursprungliga variabeln:
$$- 2 \sin{\left({\color{red}\left(u\right)} \right)} \frac{d}{dx} \left(2 x\right) = - 2 \sin{\left({\color{red}\left(2 x\right)} \right)} \frac{d}{dx} \left(2 x\right)$$Tillämpa konstantfaktorregeln $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ med $$$c = 2$$$ och $$$f{\left(x \right)} = x$$$:
$$- 2 \sin{\left(2 x \right)} {\color{red}\left(\frac{d}{dx} \left(2 x\right)\right)} = - 2 \sin{\left(2 x \right)} {\color{red}\left(2 \frac{d}{dx} \left(x\right)\right)}$$Tillämpa potensregeln $$$\frac{d}{dx} \left(x^{n}\right) = n x^{n - 1}$$$ med $$$n = 1$$$, det vill säga $$$\frac{d}{dx} \left(x\right) = 1$$$:
$$- 4 \sin{\left(2 x \right)} {\color{red}\left(\frac{d}{dx} \left(x\right)\right)} = - 4 \sin{\left(2 x \right)} {\color{red}\left(1\right)}$$Alltså, $$$\frac{d}{dx} \left(2 \cos{\left(2 x \right)}\right) = - 4 \sin{\left(2 x \right)}$$$.
Således, $$$\frac{d^{2}}{dx^{2}} \left(\sin{\left(2 x \right)}\right) = - 4 \sin{\left(2 x \right)}$$$.
Svar
$$$\frac{d^{2}}{dx^{2}} \left(\sin{\left(2 x \right)}\right) = - 4 \sin{\left(2 x \right)}$$$A