1
Let a0,a1, ,a23 be real numbers such that (1+ 25x )23= i=023ai xi for every real number x. Let ar be the largest among the numbers aj for 0 j 23. Then the value of r is .
Answer
6
Solution
ak=23Ck ( 25 )k, all positive.
ak+1ak= 23-kk+1 25 1 46-2k 5k+5 k 417 5.86.
So ak increases up to k=6 and decreases after it: largest is a6.
Answer: 6
JEE Advanced 2025 Paper 2