Đạo hàm bậc \(21\) của hàm số \(f\left( x \right) = \cos \left( {x + a} \right)\) là
A.\({f^{\left( {21} \right)}}\left( x \right) = \sin \left( {x + a + \dfrac{\pi }{2}} \right)\)
B.\({f^{\left( {21} \right)}}\left( x \right) = - \sin \left( {x + a + \dfrac{\pi }{2}} \right)\)
C.\({f^{\left( {21} \right)}}\left( x \right) = - \cos \left( {x + a + \dfrac{\pi }{2}} \right)\)
D.\({f^{\left( {21} \right)}}\left( x \right) = \cos \left( {x + a + \dfrac{\pi }{2}} \right)\)
A.\({f^{\left( {21} \right)}}\left( x \right) = \sin \left( {x + a + \dfrac{\pi }{2}} \right)\)
B.\({f^{\left( {21} \right)}}\left( x \right) = - \sin \left( {x + a + \dfrac{\pi }{2}} \right)\)
C.\({f^{\left( {21} \right)}}\left( x \right) = - \cos \left( {x + a + \dfrac{\pi }{2}} \right)\)
D.\({f^{\left( {21} \right)}}\left( x \right) = \cos \left( {x + a + \dfrac{\pi }{2}} \right)\)
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Hóa Học lớp 12
