Mark the correct alternative in the following : If in the expansion of (1 + y) n , the coefficients of 5 th , 6 th and 7 th terms are in A.P., then n is equal to

Question

Philoid · Accepted Answer

Given:

T₅; T₆& T₇

Since T₅ , T₆ & T₇ are in AP

Then; 2(T₆) = T₅ + T₇

i.e.

⇒ 30+(n-4) (n-5)-12(n-4)=0

⇒30+n²-9n+20-12n+48=0

⇒n²-21n+98=0

⇒ (n-7) (n-14)=0

⇒n=7,14

Mark the correct alternative in the following :If in the expansion of (1 + y)n, the coefficients of 5th, 6th and 7th terms are in A.P., then n is equal to

Mark the correct alternative in the following :
If in the expansion of (1 + y)ⁿ, the coefficients of 5^th, 6^th and 7^th terms are in A.P., then n is equal to