Resembling Resemblence -2

Calculus Level 5

I = 0 log ( 1 + x 4 + 15 A 1 + x 2 + 3 A ) ( 1 + x 2 ) log x d x = π N 2 ( N + O P Q ) I=\displaystyle\int_{0}^{\infty}\dfrac{\log\left(\frac{1+x^{4+\sqrt{15\vphantom{\large A}}}}{1+x^{2+\sqrt{3\vphantom{\large A}}}}\right)}{\left(1+x^2\right)\log x}\mathrm dx=\dfrac{\pi}{N^2}\left(N+\sqrt{O}\sqrt{P-\sqrt{Q}}\right) .

Then Find N + O + P + Q N+O+P+Q


Also try Part -1 and Part-3

1)P,Q are co-prime


The answer is 16.

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1 solution

Kartik Sharma
Aug 22, 2015

It looks really hard and forces you to think hard but a really big heartbreak comes when you notice the actual solution.

I ( a ) = 0 l o g ( 1 + x a ) ( 1 + x 2 ) l o g x d x \displaystyle I(a) = \int_{0}^{\infty}{\frac{log\left(1+{x}^{a}\right)}{\left(1+{x}^{2}\right)log x} \ dx}

Now x 1 x x \rightarrow \frac{1}{x} ,

I ( a ) = 0 l o g ( 1 + x a ) ( 1 + x 2 ) l o g ( 1 x ) d x + 0 l o g ( x a ) ( 1 + x 2 ) l o g x d x \displaystyle I(a) = \int_{0}^{\infty}{\frac{log\left(1+{x}^{a}\right)}{\left(1+{x}^{2}\right)log\left(\frac{1}{x}\right)} \ dx} + \int_{0}^{\infty}{\frac{log({x}^{a})}{(1+{x}^{2}) log x} \ dx}

I ( a ) = I ( a ) + a 0 1 1 + x 2 d x \displaystyle I(a) = - I(a) + a \int_{0}^{\infty}{\frac{1}{1+{x}^{2}} \ dx}

I ( a ) = a 2 ( t a n 1 ( ) t a n 1 ( 0 ) ) \displaystyle I(a) = \frac{a}{2}\left({tan}^{-1}(\infty) - {tan}^{-1}(0)\right)

I ( a ) = a π 4 \displaystyle I(a) = \boxed{\frac{a \ \pi}{4}}

see

Aman Rajput - 5 years, 9 months ago

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