Question

If sum of the coefficients of x7 and x4 in the expansion of 

Solution

Correct option is

ab = 1

         

For the coefficient of x7 set 22 – 3r = 7 or r = 5 for the coefficient of x4r= 6.

SIMILAR QUESTIONS

Q1

If the fifth term in the expansion of  does not depend upon x, then  equals

Q2

 the greatest term in absolute value in the expansion of (a +b)50 is

Q3

Coefficient of the term independent of x in the ex pansion of  is

Q4

Value (s) of x for which the fourth term in the ex pansion of  is 40 is (are)

Q6

If x2r occurs in  then n – 2r must be of the form

Q7

If the coefficient of rth, (r + 1)th and (r  + 2)th terms are in A.P., then n is a root of the equation

Q8

 

 then n must be equal to

Q9

If in the expansion of (21/3 + 3–1/3)n, the ratio of the 7th term from the beginning to the 7th terms from the end is 1: 6, then n is equal to

Q10

Coefficient of x9 in the expansion of