The correct answer is: \(=x\,tanx+log|cosx|+C\) Let \(I=∫xsec^2x dx\) Taking \(x\) as first function and \(sec^2 x\) as second function and integrating by parts,we obtain \(I=x∫sec^2x dx-∫[{{\frac{d}{dx} x}∫sec^2x\, dx}]dx\) \(=x\,tanx-∫1\,.tanx. dx\) \(=x\,tanx+log|cosx|+C\)
The number of formulas used to decompose the given improper rational functions is given below. By using the given expressions, we can quickly write the integrand as a sum of proper rational functions.