integrate 8

IIT JEE 2015 Tutorials › Calculus questions › integrate 8

integrate:
(cos5x + cos4x)/(1 - 2cos3x)

#Mathematics #Calculus

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8 Answers

39

Dr.House ·2009-02-13 08:29:39

this is a good one. according to me it would be better if u remember the solution of this which i am going to post below.

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39

Dr.House ·2009-02-13 08:34:47

given integral

=2(cos9x/2cosx/2)/1-2(2cos²3x/2-1) dx
now multiply and divide by cos3x/2

=2(cosx/2cos3x/2cos9x/2)/(3cos3x/2-4cos³3x/2)dx
=2(cosx/2cos3x/2cos9x/2)/-cos9x/2 dx

=-2cosx/2cos3x/2 dx

= -(cos2x+cosx)dx

therefore the answer is -sin2x/2 - sinx

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1

ankit mahapatra ·2009-02-13 08:46:48

Perfect . Only +c is remaining.

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39

Dr.House ·2009-02-13 08:48:32

thanks

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11

Subash ·2009-02-13 08:52:55

gr88 solution math

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1

skygirl ·2009-02-13 08:53:24

y remember ??

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39

Dr.House ·2009-02-13 08:54:23

didi, this is one of the typical types i have seen among many that i have solved thats why...............

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skygirl ·2009-02-13 09:06:36

okie... nice trick ..

can be solevd even widout knowing the trick .. :)

tho a bit two or three more steps...

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Your Answer

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