Fundamentholfundamenthol
JEE Advanced2025Paper 2MATH-III
Q.

Let

Then the value of

is ________.

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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