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← JEE Main 2017 · 2 Apr · Shift 1
MathematicsSingle correct+4 / -1Question 74 of 90

JEE Main 2017 · 2 Apr · Shift 1, Mathematics question 74

Let In=∫tan⁡nx dxI_n=\displaystyle\int\tan^nx\,dx, (n>1)(n>1). If I4+I6=atan⁡5x+bx5+CI_4+I_6=a\tan^5x+bx^5+C, where C is a constant of integration, then the ordered pair (a, b) is equal to :

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Answer and worked solution

Official answer: A

I4+I6=∫tan⁡4x(1+tan⁡2x) dx=∫tan⁡4xsec⁡2x dx=tan⁡5x5+CI_4+I_6=\int\tan^4x(1+\tan^2x)\,dx=\int\tan^4x\sec^2x\,dx=\dfrac{\tan^5x}5+C. So (a,b)=(15,0)(a,b)=\left(\frac15,0\right).