JEE Main 2020 · 6 September · Morning Shift · Mathematics · Indefinite Integration
C. 50505051\dfrac{5050}{5051}50515050
Given
α=I2I1=∫01(1−x50)101dx∫01(1−x50)100dx\alpha = \dfrac{{I}_{2}}{{I}_{1}} = \dfrac{{∫}_{0}^{1}{\left(1 - {x}^{50}\right)}^{101}dx}{{∫}_{0}^{1}{\left(1 - {x}^{50}\right)}^{100}dx}α=I1I2=∫01(1−x50)100dx∫01(1−x50)101dxNow,
I2=∫01(1−x50)(1−x50)100dx{I}_{2} = {∫}_{0}^{1}\left(1 - {x}^{50}\right){\left(1 - {x}^{50}\right)}^{100}dxI2=∫01(1−x50)(1−x50)100dxI2=I1−∫01x.x49(1−x50)100dx{I}_{2} = {I}_{1} - {∫}_{0}^{1}{x}_{.}{x}^{49}{\left(1 - {x}^{50}\right)}^{100}dxI2=I1−∫01x.x49(1−x50)100dxI2=I1−[−x(1−x50)1015050]01−∫01(1−x50)1015050dx{I}_{2} = {I}_{1} - {\left[\dfrac{- x{\left(1 - {x}^{50}\right)}^{101}}{5050}\right]}_{0}^{1} - {∫}_{0}^{1}\dfrac{{\left(1 - {x}^{50}\right)}^{101}}{5050}dxI2=I1−[5050−x(1−x50)101]01−∫015050(1−x50)101dxI2=I1−I25050{I}_{2} = {I}_{1} - \dfrac{{I}_{2}}{5050}I2=I1−5050I2⇒α=I2I1=50505051⇒ \alpha = \dfrac{{I}_{2}}{{I}_{1}} = \dfrac{5050}{5051}⇒α=I1I2=50515050