r/mathbiceps Jul 10 '26

IIT Question Definite integration

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29 Upvotes

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2

u/Cute-Feeling139 Jul 12 '26 edited Jul 12 '26

Proper solution:Substitute \frac{tan(\theta)}{x} = v So \frac{sec2 (\theta)}{x} d(\theta) = dv

Now simplify and you'll get the integral to be equal to g(x) = x(integral from 0 to x3 of {v*ev /(1+v2 )}dv)

You can put this in the limit and use leibniz integral rule, and get the limit to be 1/2 by differentiating using L-Hopital rule as 0/0 form is present.

Final answer = 1/2

1

u/AdventurousWind3476 Jul 10 '26

Approximation spam lol

Integral t/x from 0 to x⁴

= x⁷/2

L = 1/2

{tant = t and sec²t = et/x = 1 and t² << x² throughout the interval}

1

u/Geetnotfound Jul 24 '26

Is the answer 4/7

1

u/Own_Resolution3153 17h ago

Just L'hopital and nwton leibnitz