Afgeleide van $$$e^{x} + \sin{\left(y z \right)}$$$ naar $$$y$$$

De afgeleide van een som/verschil is de som/het verschil van de afgeleiden:

$${\color{red}\left(\frac{d}{dy} \left(e^{x} + \sin{\left(y z \right)}\right)\right)} = {\color{red}\left(\frac{d}{dy} \left(e^{x}\right) + \frac{d}{dy} \left(\sin{\left(y z \right)}\right)\right)}$$

De functie $$$\sin{\left(y z \right)}$$$ is de samenstelling $$$f{\left(g{\left(y \right)} \right)}$$$ van twee functies $$$f{\left(u \right)} = \sin{\left(u \right)}$$$ en $$$g{\left(y \right)} = y z$$$.

Pas de kettingregel $$$\frac{d}{dy} \left(f{\left(g{\left(y \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dy} \left(g{\left(y \right)}\right)$$$ toe:

$${\color{red}\left(\frac{d}{dy} \left(\sin{\left(y z \right)}\right)\right)} + \frac{d}{dy} \left(e^{x}\right) = {\color{red}\left(\frac{d}{du} \left(\sin{\left(u \right)}\right) \frac{d}{dy} \left(y z\right)\right)} + \frac{d}{dy} \left(e^{x}\right)$$

De afgeleide van de sinus is $$$\frac{d}{du} \left(\sin{\left(u \right)}\right) = \cos{\left(u \right)}$$$:

$${\color{red}\left(\frac{d}{du} \left(\sin{\left(u \right)}\right)\right)} \frac{d}{dy} \left(y z\right) + \frac{d}{dy} \left(e^{x}\right) = {\color{red}\left(\cos{\left(u \right)}\right)} \frac{d}{dy} \left(y z\right) + \frac{d}{dy} \left(e^{x}\right)$$

Keer terug naar de oorspronkelijke variabele:

$$\cos{\left({\color{red}\left(u\right)} \right)} \frac{d}{dy} \left(y z\right) + \frac{d}{dy} \left(e^{x}\right) = \cos{\left({\color{red}\left(y z\right)} \right)} \frac{d}{dy} \left(y z\right) + \frac{d}{dy} \left(e^{x}\right)$$

Pas de regel van de constante factor $$$\frac{d}{dy} \left(c f{\left(y \right)}\right) = c \frac{d}{dy} \left(f{\left(y \right)}\right)$$$ toe met $$$c = z$$$ en $$$f{\left(y \right)} = y$$$:

$$\cos{\left(y z \right)} {\color{red}\left(\frac{d}{dy} \left(y z\right)\right)} + \frac{d}{dy} \left(e^{x}\right) = \cos{\left(y z \right)} {\color{red}\left(z \frac{d}{dy} \left(y\right)\right)} + \frac{d}{dy} \left(e^{x}\right)$$

De afgeleide van een constante is $$$0$$$:

$$z \cos{\left(y z \right)} \frac{d}{dy} \left(y\right) + {\color{red}\left(\frac{d}{dy} \left(e^{x}\right)\right)} = z \cos{\left(y z \right)} \frac{d}{dy} \left(y\right) + {\color{red}\left(0\right)}$$

Pas de machtsregel $$$\frac{d}{dy} \left(y^{n}\right) = n y^{n - 1}$$$ toe met $$$n = 1$$$, met andere woorden, $$$\frac{d}{dy} \left(y\right) = 1$$$:

$$z \cos{\left(y z \right)} {\color{red}\left(\frac{d}{dy} \left(y\right)\right)} = z \cos{\left(y z \right)} {\color{red}\left(1\right)}$$

Dus, $$$\frac{d}{dy} \left(e^{x} + \sin{\left(y z \right)}\right) = z \cos{\left(y z \right)}$$$.