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Turunan dari $$$x^{4} \cos{\left(x \right)}$$$
Kalkulator terkait: Kalkulator Turunan
Masukan Anda
Temukan $$$\frac{d}{dx} \left(x^{4} \cos{\left(x \right)}\right)$$$.
Solusi
Misalkan $$$H{\left(x \right)} = x^{4} \cos{\left(x \right)}$$$.
Ambil logaritma pada kedua ruas: $$$\ln\left(H{\left(x \right)}\right) = \ln\left(x^{4} \cos{\left(x \right)}\right)$$$
Tulis ulang ruas kanan menggunakan sifat-sifat logaritma: $$$\ln\left(H{\left(x \right)}\right) = 4 \ln\left(x\right) + \ln\left(\cos{\left(x \right)}\right)$$$.
Diferensiasikan secara terpisah kedua sisi persamaan: $$$\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right) = \frac{d}{dx} \left(4 \ln\left(x\right) + \ln\left(\cos{\left(x \right)}\right)\right)$$$.
Turunkan ruas kiri dari persamaan.
Fungsi $$$\ln\left(H{\left(x \right)}\right)$$$ merupakan komposisi $$$f{\left(g{\left(x \right)} \right)}$$$ dari dua fungsi $$$f{\left(u \right)} = \ln\left(u\right)$$$ dan $$$g{\left(x \right)} = H{\left(x \right)}$$$.
Terapkan aturan rantai $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:
$${\color{red}\left(\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right)\right)} = {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(H{\left(x \right)}\right)\right)}$$Turunan dari logaritma natural adalah $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:
$${\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(H{\left(x \right)}\right) = {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(H{\left(x \right)}\right)$$Kembalikan ke variabel semula:
$$\frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{{\color{red}\left(u\right)}} = \frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{{\color{red}\left(H{\left(x \right)}\right)}}$$Dengan demikian, $$$\frac{d}{dx} \left(\ln\left(H{\left(x \right)}\right)\right) = \frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{H{\left(x \right)}}$$$.
Turunkan ruas kanan persamaan.
Turunan dari jumlah/selisih adalah jumlah/selisih dari turunan:
$${\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x\right) + \ln\left(\cos{\left(x \right)}\right)\right)\right)} = {\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x\right)\right) + \frac{d}{dx} \left(\ln\left(\cos{\left(x \right)}\right)\right)\right)}$$Fungsi $$$\ln\left(\cos{\left(x \right)}\right)$$$ merupakan komposisi $$$f{\left(g{\left(x \right)} \right)}$$$ dari dua fungsi $$$f{\left(u \right)} = \ln\left(u\right)$$$ dan $$$g{\left(x \right)} = \cos{\left(x \right)}$$$.
Terapkan aturan rantai $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:
$${\color{red}\left(\frac{d}{dx} \left(\ln\left(\cos{\left(x \right)}\right)\right)\right)} + \frac{d}{dx} \left(4 \ln\left(x\right)\right) = {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(\cos{\left(x \right)}\right)\right)} + \frac{d}{dx} \left(4 \ln\left(x\right)\right)$$Turunan dari logaritma natural adalah $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:
$${\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(\cos{\left(x \right)}\right) + \frac{d}{dx} \left(4 \ln\left(x\right)\right) = {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(\cos{\left(x \right)}\right) + \frac{d}{dx} \left(4 \ln\left(x\right)\right)$$Kembalikan ke variabel semula:
$$\frac{d}{dx} \left(4 \ln\left(x\right)\right) + \frac{\frac{d}{dx} \left(\cos{\left(x \right)}\right)}{{\color{red}\left(u\right)}} = \frac{d}{dx} \left(4 \ln\left(x\right)\right) + \frac{\frac{d}{dx} \left(\cos{\left(x \right)}\right)}{{\color{red}\left(\cos{\left(x \right)}\right)}}$$Turunan fungsi kosinus adalah $$$\frac{d}{dx} \left(\cos{\left(x \right)}\right) = - \sin{\left(x \right)}$$$:
$$\frac{d}{dx} \left(4 \ln\left(x\right)\right) + \frac{{\color{red}\left(\frac{d}{dx} \left(\cos{\left(x \right)}\right)\right)}}{\cos{\left(x \right)}} = \frac{d}{dx} \left(4 \ln\left(x\right)\right) + \frac{{\color{red}\left(- \sin{\left(x \right)}\right)}}{\cos{\left(x \right)}}$$Terapkan aturan kelipatan konstanta $$$\frac{d}{dx} \left(c f{\left(x \right)}\right) = c \frac{d}{dx} \left(f{\left(x \right)}\right)$$$ dengan $$$c = 4$$$ dan $$$f{\left(x \right)} = \ln\left(x\right)$$$:
$$- \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}} + {\color{red}\left(\frac{d}{dx} \left(4 \ln\left(x\right)\right)\right)} = - \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}} + {\color{red}\left(4 \frac{d}{dx} \left(\ln\left(x\right)\right)\right)}$$Turunan dari logaritma natural adalah $$$\frac{d}{dx} \left(\ln\left(x\right)\right) = \frac{1}{x}$$$:
$$- \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}} + 4 {\color{red}\left(\frac{d}{dx} \left(\ln\left(x\right)\right)\right)} = - \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}} + 4 {\color{red}\left(\frac{1}{x}\right)}$$Sederhanakan:
$$- \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}} + \frac{4}{x} = - \tan{\left(x \right)} + \frac{4}{x}$$Dengan demikian, $$$\frac{d}{dx} \left(4 \ln\left(x\right) + \ln\left(\cos{\left(x \right)}\right)\right) = - \tan{\left(x \right)} + \frac{4}{x}$$$.
Dengan demikian, $$$\frac{\frac{d}{dx} \left(H{\left(x \right)}\right)}{H{\left(x \right)}} = - \tan{\left(x \right)} + \frac{4}{x}$$$.
Oleh karena itu, $$$\frac{d}{dx} \left(H{\left(x \right)}\right) = \left(- \tan{\left(x \right)} + \frac{4}{x}\right) H{\left(x \right)} = x^{3} \left(- x \tan{\left(x \right)} + 4\right) \cos{\left(x \right)}$$$.
Jawaban
$$$\frac{d}{dx} \left(x^{4} \cos{\left(x \right)}\right) = x^{3} \left(- x \tan{\left(x \right)} + 4\right) \cos{\left(x \right)}$$$A