My favourite IIT-JEE Maths question

Although I'm in Class 12,but I couldn't stop myself from taking a glance at this year's JEE Math's questions. I found this question to be very intriguing and so I thought of sharing it with my Brilliant friends.

For aRa \in R (set of real numbers) , a1a \neq -1, limn1a+2a++na(n+1)a1[(na+1)+(na+2)++(na+n)]=160lim_{n \to \infty}\frac{1^a+2^a+ \ldots +n^a}{(n+1)^{a-1}[(na+1)+(na+2)+\ldots+(na+n)]}= \frac{1}{60} Then a=?a=?

#LearningResources #Math

Note by Shubham Srivastava
7 years, 11 months ago

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Comments

The answers are 7 and 172\frac{-17}{2}. The trick here was to first express the limit in form of summation(Σ\Sigma) and then change summation in definite integration(01\int_0^1).

Shubham Srivastava - 7 years, 11 months ago

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8888

Pc mishra - 3 years, 7 months ago

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Log questions based on first significant digit

Pc mishra - 3 years, 7 months ago

Please solve your question

Pc mishra - 3 years, 7 months ago

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7 answer first bind up the expression \this then using sum of limits

Pranjal Panwar - 1 year, 10 months ago

i just did trail and error....

Gunadeep Reddy - 7 years, 11 months ago

Write a comment or ask a question...can you give me the solution

Ayobami Salau - 5 years, 8 months ago

were there any options given??

Gunadeep Reddy - 7 years, 11 months ago

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Yes, its a multiple correct answers question.

Shubham Srivastava - 7 years, 11 months ago

a=7

Gunadeep Reddy - 7 years, 11 months ago

how?

Kiran Patel - 7 years, 11 months ago

You got it?

Aabhas Mathur - 7 years, 11 months ago

I got two answers....a=7 and a= -7/5, but the answer key gives only one. I got a quadratic equation at the end.

Anybody else got the same result?

Rish Malviya - 7 years, 11 months ago

a=7 is only accepted

Aditya Vaikunt - 5 years, 2 months ago

Answer is 7 or -17/2 ....i guess...

diali kundu - 3 years, 4 months ago

Determine K so that 2÷3 ,K and 5÷3×k are three consecutive term of an AP

Manoj Kumar Yadav - 3 years, 4 months ago

what's JEE?

Catherine Wooller - 7 years, 11 months ago

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It's the most competitive Engineering Entrance Exam in India.It questions on Physics,Chemistry and Mathematics......

A Former Brilliant Member - 7 years, 11 months ago

joint entrance examinations

Swastik Mahapatra - 7 years, 6 months ago

how to improve maths skill

Chandana Pechetti - 6 years, 5 months ago

they really gave such easy questions this year?JEE has been diluted.

A Former Brilliant Member - 7 years, 11 months ago

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Good thing you didn't see the Physics section...

Rish Malviya - 7 years, 11 months ago

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I took a look,and I see no reason of deviating from my stand.I didn't see anything much innovative,except for a hydrostatics problem in paper 1,and a couple of matching type questions in paper 2.Even those were not really tough,just needed keeping your head cool.Trust me,JEE has seen much better days.

A Former Brilliant Member - 7 years, 11 months ago

the chemistry questions were tough, but the maths and the physics questions were found very easy to me.

Shourya Pandey - 7 years, 11 months ago
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