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242xx24dx\int_{2}^{4}\frac{2}{x\sqrt{x^{2}-4}}dx

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Q. 242xx24dx\int_{2}^{4}\frac{2}{x\sqrt{x^{2}-4}}dx
  1. Substitution and Simplification: Substitute x=2sec(θ)x = 2\sec(\theta) into the integral and simplify.2xx24dx=22sec(θ)4sec2(θ)42sec(θ)tan(θ)dθ\int\frac{2}{x\sqrt{x^2-4}}dx = \int\frac{2}{2\sec(\theta)\sqrt{4\sec^2(\theta)-4}} \cdot 2\sec(\theta)\tan(\theta)d\theta =22sec(θ)4(tan2(θ)+1)42sec(θ)tan(θ)dθ= \int\frac{2}{2\sec(\theta)\sqrt{4(\tan^2(\theta)+1)-4}} \cdot 2\sec(\theta)\tan(\theta)d\theta =22sec(θ)4tan2(θ)2sec(θ)tan(θ)dθ= \int\frac{2}{2\sec(\theta)\sqrt{4\tan^2(\theta)}} \cdot 2\sec(\theta)\tan(\theta)d\theta =22sec(θ)2tan(θ)2sec(θ)tan(θ)dθ= \int\frac{2}{2\sec(\theta) \cdot 2\tan(\theta)} \cdot 2\sec(\theta)\tan(\theta)d\theta =24tan(θ)2sec(θ)tan(θ)dθ= \int\frac{2}{4\tan(\theta)} \cdot 2\sec(\theta)\tan(\theta)d\theta =(12)dθ= \int\left(\frac{1}{2}\right)d\theta
  2. Integration and Simplification: Integrate (12)dθ(\frac{1}{2})d\theta from 00 to π3\frac{\pi}{3}.
    (12)dθ=(12)θ\int(\frac{1}{2})d\theta = (\frac{1}{2})\theta
    Evaluating from 00 to π3\frac{\pi}{3} gives us:
    (12)θ(\frac{1}{2})\theta | from 00 to π3\frac{\pi}{3} = (12)(π3)(12)(0)=π6(\frac{1}{2})(\frac{\pi}{3}) - (\frac{1}{2})(0) = \frac{\pi}{6}
  3. Evaluation and Conversion: Convert the result back to xx. Since we made the substitution x=2sec(θ)x = 2\sec(\theta), we need to find the corresponding θ\theta values for x=2x = 2 and x=4x = 4. However, we already have these values from the substitution step: θ=0\theta = 0 when x=2x = 2 and θ=π3\theta = \frac{\pi}{3} when x=4x = 4. Therefore, the definite integral from 22 to x=2sec(θ)x = 2\sec(\theta)00 of the function x=2sec(θ)x = 2\sec(\theta)11 with respect to xx is x=2sec(θ)x = 2\sec(\theta)33.