If the ratio of the coefficients of 3rd and 4th terms in the expansion of is 1:2 then find the value of n.

Asked by Topperlearning User | 24th Apr, 2014, 08:30: AM

Expert Answer:

Given expansion is 
 

T subscript 3 over T subscript 4 equals fraction numerator n open parentheses n minus 1 close parentheses cross times 3 cross times 2 cross times 1 cross times 8 over denominator n open parentheses n minus 1 close parentheses open parentheses n minus 2 close parentheses cross times 2 cross times 1 cross times 4 end fraction equals 1 half

rightwards double arrow n minus 2 equals 12

rightwards double arrow n equals 14

Answered by  | 24th Apr, 2014, 10:30: AM