推 Qmmm:謝謝! 140.112.128.93 11/08 16:20
※ 引述《Qmmm (．．Ｑ3Ｍ．．)》之銘言：
: x (n)
: f(x) = e * sinx , 求 f (x) = ?
: 這題不能用萊不泥滋吧？請教用什麼方法？謝謝!
f' = exp(x)sinx + exp(x)cosx = exp(x)[sinx + cosx]
= exp(x)[√2][sin(x+π/4)]
f' = √2 exp(x) [sin(x+π/4)]
=>f'' = exp(x)[√2]^2[sin(x+2*π/4)]
(n)
=>f = exp(x)[√2]^n[sin(x+n*π/4)]
自己微分一兩次就會知道計算過程幾乎相同
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