Ques. 1JEE Main 2025, 22 January (Morning Shift)
If r=05 11C2r+12r+2= mn, (m,n)=1, then m-n is equal to .
Answer
2035
Solution
11Ckk+1= 12Ck+112 with k=2r+1.
Sum = 112 (12C2+12C4+ +12C12 )
Even-place coefficients of (1+x)12 add to 211, so the bracket =211-1=2047
mn= 204712 (coprime) m-n=2035
Answer: 2035