Integration (10)

Calculus Level 5

1 e e ( 1 ln x ) x 2 + ( e ln x ) 2 d x \large \int_1^e \dfrac{e (1-\ln x)}{ x^2 + (e \ln x)^2} \, dx

If the integral above is equal to π a \dfrac \pi a , find 2016 a \dfrac {2016}a .


The answer is 504.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Tanishq Varshney
Jan 24, 2016

The given integral is

1 e e ( 1 ln x ) x 2 ( 1 + ( e ln x x ) 2 ) d x \large{\displaystyle \int^{e}_{1} \frac{e(1- \ln x)}{x^2 \left(1+\left(\frac{e \ln x}{x}\right)^2 \right)} dx}

Put e ln x x = t e ( 1 ln x ) x 2 d x = d t \large{\frac{e \ln x}{x}=t \Rightarrow \frac{e(1- \ln x)}{x^2} dx=dt}

thus 0 1 1 1 + t 2 d t ( arctan ( t ) ) 0 1 = π 4 \large{\displaystyle \int^{1}_{0} \frac{1}{1+t^2} dt \Rightarrow \left( \arctan (t) \right)^{1}_{0}=\frac{\pi}{4}}

Aaditya Lanke
Dec 27, 2016

The given integral is a definite integral so on using numeric integration we can solve to an expression using the simpson's rule of numeric integration to get:

(e-1)/6(e+0.1)=0.8 approximately

Now That value is= pi/4 Thus a=4

hence 2016/a=2016/4= 504

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...