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$$$\cos{\left(e^{t} \right)}$$$의 도함수
사용자 입력
$$$\frac{d}{dt} \left(\cos{\left(e^{t} \right)}\right)$$$을(를) 구하시오.
풀이
함수 $$$\cos{\left(e^{t} \right)}$$$는 두 함수 $$$f{\left(u \right)} = \cos{\left(u \right)}$$$와 $$$g{\left(t \right)} = e^{t}$$$의 합성함수 $$$f{\left(g{\left(t \right)} \right)}$$$이다.
연쇄법칙 $$$\frac{d}{dt} \left(f{\left(g{\left(t \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dt} \left(g{\left(t \right)}\right)$$$을(를) 적용하십시오:
$${\color{red}\left(\frac{d}{dt} \left(\cos{\left(e^{t} \right)}\right)\right)} = {\color{red}\left(\frac{d}{du} \left(\cos{\left(u \right)}\right) \frac{d}{dt} \left(e^{t}\right)\right)}$$코사인의 도함수는 $$$\frac{d}{du} \left(\cos{\left(u \right)}\right) = - \sin{\left(u \right)}$$$입니다:
$${\color{red}\left(\frac{d}{du} \left(\cos{\left(u \right)}\right)\right)} \frac{d}{dt} \left(e^{t}\right) = {\color{red}\left(- \sin{\left(u \right)}\right)} \frac{d}{dt} \left(e^{t}\right)$$역치환:
$$- \sin{\left({\color{red}\left(u\right)} \right)} \frac{d}{dt} \left(e^{t}\right) = - \sin{\left({\color{red}\left(e^{t}\right)} \right)} \frac{d}{dt} \left(e^{t}\right)$$지수함수의 도함수는 $$$\frac{d}{dt} \left(e^{t}\right) = e^{t}$$$:
$$- \sin{\left(e^{t} \right)} {\color{red}\left(\frac{d}{dt} \left(e^{t}\right)\right)} = - \sin{\left(e^{t} \right)} {\color{red}\left(e^{t}\right)}$$따라서, $$$\frac{d}{dt} \left(\cos{\left(e^{t} \right)}\right) = - e^{t} \sin{\left(e^{t} \right)}$$$.
정답
$$$\frac{d}{dt} \left(\cos{\left(e^{t} \right)}\right) = - e^{t} \sin{\left(e^{t} \right)}$$$A