Funktion $$$\left(x^{3} + 4\right)^{4} \left(x^{5} + 2\right)^{2}$$$ derivaatta

Olkoon $$$H{\left(x \right)} = \left(x^{3} + 4\right)^{4} \left(x^{5} + 2\right)^{2}$$$.

Ota logaritmi yhtälön molemmilta puolilta: $$$\ln\left(H{\left(x \right)}\right) = \ln\left(\left(x^{3} + 4\right)^{4} \left(x^{5} + 2\right)^{2}\right)$$$.

Kirjoita oikea puoli uudelleen logaritmien ominaisuuksia käyttäen: $$$\ln\left(H{\left(x \right)}\right) = 4 \ln\left(x^{3} + 4\right) + 2 \ln\left(x^{5} + 2\right)$$$.

Derivoi erikseen yhtälön molemmat puolet: $$$\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right) = \frac{d}{dx} \left(4 \ln\left(x^{3} + 4\right) + 2 \ln\left(x^{5} + 2\right)\right)$$$.

Derivoi yhtälön vasen puoli.

Funktio $$$\ln\left(H{\left(x \right)}\right)$$$ on kahden funktion $$$f{\left(u \right)} = \ln\left(u\right)$$$ ja $$$g{\left(x \right)} = H{\left(x \right)}$$$ yhdistelmä $$$f{\left(g{\left(x \right)} \right)}$$$.

Sovella ketjusääntöä $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:

$${\color{red}\left(\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right)\right)} = {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(H{\left(x \right)}\right)\right)}$$

Luonnollisen logaritmin derivaatta on $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:

$${\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(H{\left(x \right)}\right) = {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(H{\left(x \right)}\right)$$

Palaa alkuperäiseen muuttujaan:

$$\frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{{\color{red}\left(u\right)}} = \frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{{\color{red}\left(H{\left(x \right)}\right)}}$$

Näin ollen, $$$\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right) = \frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{H{\left(x \right)}}$$$.

Derivoi yhtälön oikea puoli.

Summan/erotuksen derivaatta on derivaattojen summa/erotus:

$${\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x^{3} + 4\right) + 2 \ln\left(x^{5} + 2\right)\right)\right)} = {\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x^{3} + 4\right)\right) + \frac{d}{dx} \left(2 \ln\left(x^{5} + 2\right)\right)\right)}$$

Sovella vakion kerroinsääntöä $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ käyttäen $$$c = 4$$$ ja $$$f{\left(x \right)} = \ln\left(x^{3} + 4\right)$$$:

$${\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x^{3} + 4\right)\right)\right)} + \frac{d}{dx} \left(2 \ln\left(x^{5} + 2\right)\right) = {\color{red}\left(4 \frac{d}{dx} \left(\ln\left(x^{3} + 4\right)\right)\right)} + \frac{d}{dx} \left(2 \ln\left(x^{5} + 2\right)\right)$$

Sovella vakion kerroinsääntöä $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ käyttäen $$$c = 2$$$ ja $$$f{\left(x \right)} = \ln\left(x^{5} + 2\right)$$$:

$${\color{red}\left(\frac{d}{dx} \left(2 \ln\left(x^{5} + 2\right)\right)\right)} + 4 \frac{d}{dx} \left(\ln\left(x^{3} + 4\right)\right) = {\color{red}\left(2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right)\right)} + 4 \frac{d}{dx} \left(\ln\left(x^{3} + 4\right)\right)$$

Funktio $$$\ln\left(x^{3} + 4\right)$$$ on kahden funktion $$$f{\left(u \right)} = \ln\left(u\right)$$$ ja $$$g{\left(x \right)} = x^{3} + 4$$$ yhdistelmä $$$f{\left(g{\left(x \right)} \right)}$$$.

Sovella ketjusääntöä $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:

$$4 {\color{red}\left(\frac{d}{dx} \left(\ln\left(x^{3} + 4\right)\right)\right)} + 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) = 4 {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(x^{3} + 4\right)\right)} + 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right)$$

Luonnollisen logaritmin derivaatta on $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:

$$4 {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(x^{3} + 4\right) + 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) = 4 {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(x^{3} + 4\right) + 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right)$$

Palaa alkuperäiseen muuttujaan:

$$2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 \frac{d}{dx} \left(x^{3} + 4\right)}{{\color{red}\left(u\right)}} = 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 \frac{d}{dx} \left(x^{3} + 4\right)}{{\color{red}\left(x^{3} + 4\right)}}$$

Summan/erotuksen derivaatta on derivaattojen summa/erotus:

$$2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 {\color{red}\left(\frac{d}{dx} \left(x^{3} + 4\right)\right)}}{x^{3} + 4} = 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 {\color{red}\left(\frac{d}{dx} \left(x^{3}\right) + \frac{d}{dx} \left(4\right)\right)}}{x^{3} + 4}$$

Vakion derivaatta on $$$0$$$:

$$2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 \left({\color{red}\left(\frac{d}{dx} \left(4\right)\right)} + \frac{d}{dx} \left(x^{3}\right)\right)}{x^{3} + 4} = 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 \left({\color{red}\left(0\right)} + \frac{d}{dx} \left(x^{3}\right)\right)}{x^{3} + 4}$$

Sovella potenssisääntöä $$$\frac{d}{dx} \left(x^{n}\right) = n x^{n - 1}$$$, kun $$$n = 3$$$:

$$2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 {\color{red}\left(\frac{d}{dx} \left(x^{3}\right)\right)}}{x^{3} + 4} = 2 \frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right) + \frac{4 {\color{red}\left(3 x^{2}\right)}}{x^{3} + 4}$$

Funktio $$$\ln\left(x^{5} + 2\right)$$$ on kahden funktion $$$f{\left(u \right)} = \ln\left(u\right)$$$ ja $$$g{\left(x \right)} = x^{5} + 2$$$ yhdistelmä $$$f{\left(g{\left(x \right)} \right)}$$$.

Sovella ketjusääntöä $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:

$$\frac{12 x^{2}}{x^{3} + 4} + 2 {\color{red}\left(\frac{d}{dx} \left(\ln\left(x^{5} + 2\right)\right)\right)} = \frac{12 x^{2}}{x^{3} + 4} + 2 {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(x^{5} + 2\right)\right)}$$

Luonnollisen logaritmin derivaatta on $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:

$$\frac{12 x^{2}}{x^{3} + 4} + 2 {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(x^{5} + 2\right) = \frac{12 x^{2}}{x^{3} + 4} + 2 {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(x^{5} + 2\right)$$

Palaa alkuperäiseen muuttujaan:

$$\frac{12 x^{2}}{x^{3} + 4} + \frac{2 \frac{d}{dx} \left(x^{5} + 2\right)}{{\color{red}\left(u\right)}} = \frac{12 x^{2}}{x^{3} + 4} + \frac{2 \frac{d}{dx} \left(x^{5} + 2\right)}{{\color{red}\left(x^{5} + 2\right)}}$$

Summan/erotuksen derivaatta on derivaattojen summa/erotus:

$$\frac{12 x^{2}}{x^{3} + 4} + \frac{2 {\color{red}\left(\frac{d}{dx} \left(x^{5} + 2\right)\right)}}{x^{5} + 2} = \frac{12 x^{2}}{x^{3} + 4} + \frac{2 {\color{red}\left(\frac{d}{dx} \left(x^{5}\right) + \frac{d}{dx} \left(2\right)\right)}}{x^{5} + 2}$$

Vakion derivaatta on $$$0$$$:

$$\frac{12 x^{2}}{x^{3} + 4} + \frac{2 \left({\color{red}\left(\frac{d}{dx} \left(2\right)\right)} + \frac{d}{dx} \left(x^{5}\right)\right)}{x^{5} + 2} = \frac{12 x^{2}}{x^{3} + 4} + \frac{2 \left({\color{red}\left(0\right)} + \frac{d}{dx} \left(x^{5}\right)\right)}{x^{5} + 2}$$

Sovella potenssisääntöä $$$\frac{d}{dx} \left(x^{n}\right) = n x^{n - 1}$$$, kun $$$n = 5$$$:

$$\frac{12 x^{2}}{x^{3} + 4} + \frac{2 {\color{red}\left(\frac{d}{dx} \left(x^{5}\right)\right)}}{x^{5} + 2} = \frac{12 x^{2}}{x^{3} + 4} + \frac{2 {\color{red}\left(5 x^{4}\right)}}{x^{5} + 2}$$

Näin ollen, $$$\frac{d}{dx} \left(4 \ln\left(x^{3} + 4\right) + 2 \ln\left(x^{5} + 2\right)\right) = \frac{10 x^{4}}{x^{5} + 2} + \frac{12 x^{2}}{x^{3} + 4}$$$.

Tästä seuraa, että $$$\frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{H{\left(x \right)}} = \frac{10 x^{4}}{x^{5} + 2} + \frac{12 x^{2}}{x^{3} + 4}$$$.

Siispä $$$\frac{d}{dx} \left(H{\left(x \right)}\right) = \left(\frac{10 x^{4}}{x^{5} + 2} + \frac{12 x^{2}}{x^{3} + 4}\right) H{\left(x \right)} = 2 x^{2} \left(x^{3} + 4\right)^{3} \left(x^{5} + 2\right) \left(11 x^{5} + 20 x^{2} + 12\right).$$$