arthham

JEE Advanced 2018 · Integrals

The value of the integral ∫0121+3((x+1)2(1−x)6)14 dx\int_{0}^{\frac{1}{2}} \frac{1+\sqrt{3}}{\left((x+1)^{2}(1-x)^{6}\right)^{\frac{1}{4}}}\,dx is ______.

Answer: 22

Watch this solved on the board The full walkthrough, written out a line at a time with narration explaining each step as it appears. Pause anywhere and ask why a line is there. Free to watch

Or read the worked solution below. Jump to the steps ↓

Written solution

The value of the integral ∫₀^(1/2) (1+√3)/(((x+1)²(1-x)⁶)^(1/4)) dx is ______. ∫01/21+3((x+1)2(1−x)6)1/4 dx\displaystyle\int_{0}^{1/2} \dfrac{1+\sqrt{3}}{\left((x+1)^{2}(1-x)^{6}\right)^{1/4}}\,dx To find: the value of the integral\text{To find: the value of the integral} 1. simplify the denominator1.\ \text{simplify the denominator} 2. spot the antiderivative2.\ \text{spot the antiderivative} 3. apply the limits 0→1/23.\ \text{apply the limits } 0 \to 1/2 ((x+1)2(1−x)6)1/4=(x+1)1/2(1−x)3/2\left((x+1)^{2}(1-x)^{6}\right)^{1/4} = (x+1)^{1/2}(1-x)^{3/2} I=(1+3)∫01/2(x+1)−1/2(1−x)−3/2 dxI = (1+\sqrt{3})\displaystyle\int_{0}^{1/2} (x+1)^{-1/2}(1-x)^{-3/2}\,dx Find y with y′=(x+1)−1/2(1−x)−3/2\text{Find } y \text{ with } y' = (x+1)^{-1/2}(1-x)^{-3/2} y=x+11−x=(x+1)1/2(1−x)−1/2y = \sqrt{\dfrac{x+1}{1-x}} = (x+1)^{1/2}(1-x)^{-1/2} y′=12(x+1)−1/2(1−x)−1/2+12(x+1)1/2(1−x)−3/2y' = \dfrac{1}{2}(x+1)^{-1/2}(1-x)^{-1/2} + \dfrac{1}{2}(x+1)^{1/2}(1-x)^{-3/2} =12(x+1)−1/2(1−x)−3/2[(1−x)+(x+1)]=(x+1)−1/2(1−x)−3/2= \dfrac{1}{2}(x+1)^{-1/2}(1-x)^{-3/2}\left[(1-x)+(x+1)\right] = (x+1)^{-1/2}(1-x)^{-3/2} I=(1+3)[x+11−x]01/2I = (1+\sqrt{3})\left[\sqrt{\dfrac{x+1}{1-x}}\right]_{0}^{1/2} At x=1/2:1/2+11−1/2=3\text{At } x = 1/2:\quad \sqrt{\dfrac{1/2+1}{1-1/2}} = \sqrt{3} At x=0:0+11−0=1\text{At } x = 0:\quad \sqrt{\dfrac{0+1}{1-0}} = 1 I=(1+3)(3−1)I = (1+\sqrt{3})(\sqrt{3} - 1) =(3)2−12=3−1= (\sqrt{3})^{2} - 1^{2} = 3 - 1 I=2I = 2 Answer: 2\boxed{\text{Answer: } 2}

More from Integrals

All 55 Integrals questions →

Integrals: formulas and what the chapter covers →