JEE Advanced2025Paper 2MATH-III
Q.
Let
Then the value of
is ________.
Correct answer: 3
Solution
Step 1: Standard telescoping identity.
, using .
Step 2: Multiply by .
.
Step 3: Note the telescoping is not adjacent.
The pairs are . Group using .
For each , the term pairs with from the second half, doubling cancellations. After careful pairing, all terms cancel except .
Step 4: Conclude.
, so .
Therefore .
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