$\displaystyle \int \frac{1}{5+4\sec{x}} dx$ please give only hints in solving this integral ireally dont know what to do first thanks
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Try this substitution: u=tan(x/2)
whats the u here? x = 2arctan(u) dx = 2 ( 1/ (1 + u^2)) i dint understand still
$\displaystyle \sec x = \frac{(1+u^2)^2}{(1-u^2)^2} $
Originally Posted by ^_^Engineer_Adam^_^ whats the u here? x = 2arctan(u) dx = 2 ( 1/ (1 + u^2))du Yes. And cosx=(1-u^2)/(1+u^2). So this makes the integrand a rational fraction.
thanks! oh yeahhh i forgot this was all easy using trig sub... thanks a lot for the help
Last edited by ^_^Engineer_Adam^_^; Aug 3rd 2007 at 03:23 AM.
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