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← JEE Main 2014 · 19 Apr · Shift 1
MathematicsSingle correct+4 / -1Question 77 of 90

JEE Main 2014 · 19 Apr · Shift 1, Mathematics question 77

If dydx+ytan⁡x=sin⁡2x\dfrac{dy}{dx}+y\tan x=\sin2x and y(0)=1y(0)=1, then y(π)y(\pi) is equal to :

Choose one option
Answer and worked solution

Official answer: C

The integrating factor is sec⁡x\sec x: (ysec⁡x)′=2sin⁡x(y\sec x)'=2\sin x, so ysec⁡x=−2cos⁡x+cy\sec x=-2\cos x+c. y(0)=1y(0)=1 gives c=3c=3.

At x=πx=\pi: −y=2+3-y=2+3, so y(π)=−5y(\pi)=-5.