obtain Yn for y=e^ax . cos(bx + c) and
find y- e^x . cos 5x . cos 3x

Question

obtain Yn for y=e^ax . cos(bx + c) and
 find y- e^x . cos 5x . cos 3x

anonymous · Answer

whats Yn?

anonymous · Answer

nth derivative I think

anonymous · Answer

ya but obvious ..

anonymous · Answer

6 marks for this .. plz help me gettin full ans

anonymous · Answer

and it is y= e^x cos 5x cos 3x

anonymous · Answer

You want the nth derivative of y= e^x cos5x cos3x?

anonymous · Answer

ya and nth derivative of general form also

anonymous · Answer

It veeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeery complicated as a sampler : http://www.wolframalpha.com/input/?i=5th+derivative+of+y%3De%5Eax+.+cos%28bx+%2B+c%29 http://www.wolframalpha.com/input/?i=10th+derivative+of+y%3De%5Eax+.+cos%28bx+%2B+c%29

anonymous · Answer

nth derivative will get very complicated...but the derivative can be written like:

|dw:1333024955764:dw|


Now split it and take 1/2 common. I am not gonna write 1/2. 
so it becomes e^x cos8x + e^xcos2x
derivative will be e^xcos8x - 8sin8xe^x + e^xcos2x - 2sin2xe^x