JEE Main202229 Jul 2022Morning ShiftMathematicsBinomial TheoremActual
Let the ratio of the fifth term from the beginning to the fifth term from the end in the binomial expansion of 2 4 + 1 3 4 n , in the increasing powers of 1 3 4 be 6 4 : 1 . If the sixth term from the beginning is α 3 4 , then α is equal to _______.
Correct answer
0
Step-by-step solution
Given, The ratio of the fifth term from the beginning to the fifth term from the end in the binomial expansion of 2 4 + 1 3 4 n in the increasing powers of 1 3 4 be 6 4 : 1 Now according to given data we have, T 5 T n - 3 = C 4 n 2 1 / 4 n - 4 3 - 1 / 4 4 C n - 4 n 2 1 / 4 4 3 - 1 / 4 n - 4 = 6 4 1 ⇒ 2 n - 8 4 3 n - 8 4 = 6 1 / 4 ⇒ 6 n - 8 = 6 ⇒ n - 8 = 1 ⇒ n = 9 So, T 6 = C 5 9 2 1 / 4 4 3 - 1 / 4 5 = 84 3 4 Now comparing with T 6 = α 3 4 , We get α = 84