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## Homework Statement

∫ -60x

^{3}tan(3x

^{4})dx

## Homework Equations

integration rules

## The Attempt at a Solution

=> ∫ -60x

^{3}tan(3x

^{4})dx

=> u = (3x

^{4})

=> du = 12x

^{3}dx

=> (-5)∫ (1/5)-60x

^{3}tan(3x

^{4})dx

=> -5 ∫ tan u

=> -5

**.**-ln cos(u) , where u = (3x

^{4})

=> 5

**.**ln cos (3x

^{4})

I am using this integral to check an original equation which I differentiated which was:

ln (cos

^{5}(3x

^{4}) , so where have I gone wrong when integrating, because I'm not getting it back ? ( I have started just learning the basics of integration so be nice :) )

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