Question
Question: If n−(1−24x+1)n} = a0 + a1x + ..... + a5x5, then n equals –
A
11
B
9
C
10
D
None of these
Answer
11
Explanation
Solution
4x+11 {(1+24x+1)n−(1−24x+1)n}
= 2n4x+11 [2{nC1 4x+1 + nC3 (4x+1)3 + .......}]
= 2n−11 [nC1 + nC3 (4x+1)2 + nC5 (4x+1)4 + ......]
Also, L.H.S = a0 + a1x + ...... + a5x5, so the last term must be nC11 (4x+1)10.
\ The value of n is 11.