If the coefficients of the middle terms in the binomial expansions of (1+ x)26 and (1- x)28, 0, are equal, then the value of is :
- 1
- 1413
- 277
- 727
Answer
(4) 727
Solution
(1+ x)26 has 27 terms; middle term T14=26C13( x)13
coefficient =26C13 13
(1- x)28 has 29 terms; middle term T15=28C14(- x)14
coefficient =28C14 14
Equal coefficients, 0 : = 26C1328C14
28C14= 28!14! 14!= 28 2714 14 26!13! 13!= 277 26C13
= 727
Answer: (4)