Binomial TheoremHard
Question
If the coefficients of the three successive terms in the binomial expansion of (1 + x)n are in the ratio 1 : 7 : 42, then the first of these terms in the expansion is
Options
A.6th
B.7th
C.8th
D.9th
Solution
nCr-1 : nCr : nCr+1
⇒ 8r = n + 1
⇒ 7r = n − 6
⇒ r = 7
⇒ 8r = n + 1
⇒ 7r = n − 6
⇒ r = 7
Create a free account to view solution
View Solution FreeMore Binomial Theorem Questions
The sum of (n +1) terms of the series C02+ 3C12 + 5C22 + ..... is -...The value of the expression is ....The number of seven digit integers, with sum of the digits equal to 10 and formed by using the digits 1, 2 and 3 only, i...If (1 + x)n = C0 + C1x + C2x2 +...+ Cnxn, then C0Cr + C1Cr + 1 + C2Cr+2 + .....+ Cn-r Cn is equal to-...The sum of the terms of the series [3.nC0 − 8.nC1 + 13.nC2 − 18. nC3 + .....+ (n + 1)] is-...