JEE Main 2014 · 6 April · Mathematics · Indefinite Integration
D. xex+1x+cx{e}^{x + \dfrac{1}{x}} + cxex+x1+c
∫(1+x−1x)ex+1xdx=∫ex+1xdx+∫x(1−1x2)ex+1xdx∫ \left(1 + x - \dfrac{1}{x}\right){e}^{x + \dfrac{1}{x}}dx = ∫ {e}^{x + \dfrac{1}{x}}dx + ∫ x\left(1 - \dfrac{1}{{x}^{2}}\right){e}^{x + \dfrac{1}{x}}dx∫(1+x−x1)ex+x1dx=∫ex+x1dx+∫x(1−x21)ex+x1dx
Integrating ∫x⏟I.(1−1x2)ex+1x⏟IIdx∫ \mathop{\mathop{x}_{⏟}}_{I} . \mathop{\mathop{( 1 - \dfrac{1}{{x}^{2}} ){e}^{x + \dfrac{1}{x}}}_{⏟}}_{II}dx∫x⏟I.(1−x21)ex+x1⏟IIdx, by parts
I=xex+1x−∫ex+1xdx+cI = x{e}^{x + \dfrac{1}{x}} - ∫ {e}^{x + \dfrac{1}{x}}dx + cI=xex+x1−∫ex+x1dx+c
=∫(1+x−1x)ex+1xdx=∫ex+1xdx+xex+1x−∫ex+1xdx+c= ∫ \left(1 + x - \dfrac{1}{x}\right){e}^{x + \dfrac{1}{x}}dx = ∫ {e}^{x + \dfrac{1}{x}}dx + x{e}^{x + \dfrac{1}{x}} - ∫ {e}^{x + \dfrac{1}{x}}dx + c=∫(1+x−x1)ex+x1dx=∫ex+x1dx+xex+x1−∫ex+x1dx+c
=xex+1x+c= x{e}^{x + \dfrac{1}{x}} + c=xex+x1+c, where ccc is the constant of integration.