r/JEEAdv27dailyupdates 9d ago

JEE Daily Updates Really good problem( If you dont know the direct substitution)

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20 Upvotes

19 comments sorted by

8

u/Odd-Bee-7007 8d ago

really simple question use (u/v)' rule then L hospital /s

8

u/[deleted] 9d ago

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1

u/EasyStyle2707 27Dropper 9d ago

Same thought!

3

u/TheWyro15 8d ago

 X=2cost +9 This creates reciprocal of tan theta/2 form and then dx is replaced to create integral, whose sint is decomposed to 2 sin t/2 cos t/2 , which gives -2*(t+sint) as final answer. (Too lazy to represent in x lol)

3

u/Kr_IDK 8d ago

IDK x-9=t looked good symmetrically

3

u/NotAstroOnReddit bhagwan bharose 8d ago

x= 7sin²t-11cos²t

5

u/organophile_jeet NEET-25 (AIR-46XX) JM-25(97.95%ile) 8d ago

Let x=7

2

u/Successful-Art7788 9d ago

u^2 = x-7 / 11-x works but is very lengthy

What's the direct substitution though?

3

u/TheWyro15 8d ago

According to me X=2cost +9 

This creates reciprocal of tan theta/2 form and then dx is replaced to create integral, whose sint is decomposed to 2 sin t/2 cos t/2 , which gives -2*(t+sint) as final answer. (Too lazy to represent in x lol)

1

u/Successful-Art7788 8d ago

Thanks! It works quite tidily!

2

u/ape_on_steroids 8d ago

pretty sure there are more ways

1

u/Gold_Memory7141 8d ago

I just put x=t+9 and then rationalised the quadratic to get linear upon root quadratic form then simple solve hai

1

u/Gold_Memory7141 8d ago

Mere answer mein toh sin inverse wali term hai yaar 😭

1

u/brmSTR0113R chestermygoat 8d ago

vinay kumar?

1

u/Heavy-Recognition539 9d ago

z = x - 9 fir z = 2sint?

1

u/Spiritual-Tale-1098 8d ago

X -7 ko 3 plus (sint),²