Please explain with steps
(a) y= e^3x cos2x
dy/dx = ?
d^2y/dx^2 = ?
(b) y= e^4x + e^-x
dy/dx = ?
d^2y/dx^2 = ?
Questions on differential equations, who can help me?
2011-10-25 11:39 am
回答 (1)
2011-10-25 12:31 pm
✔ 最佳答案
y`= (e^3x cos2x)`= (e^3x)` cos2x + e^3x (cos2x)` = (3e^3x) cos2x - e^3x (2sin2x)y`` =((3e^3x) cos2x - e^3x (2sin2x))` = (3e^3x)` cos2x + (3e^3x) (cos2x)` - (e^3x)` (2sin2x) - e^3x (2sin2x)`=(9e^3x) cos2x - (3e^3x) (2sin2x) - (3e^3x) (2sin2x) - e^3x (4cos2x)
參考: .
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