NCERT Class 11-Math's: Chapter –8 Binomial Theorem Part 8

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Question 14:

Find in the binomial f the ratio of 7^th term from the beginning to the 7^th term from the end is .

Answer:

The given expression is

General Term

7^th term from the end term from the beginning

term from the beginning

So,

According to the question, we get

Hence, the required value of is

Question 15:

In the expansion of if the sum of odd terms is denoted by and the sum of even term by E.

Then prove that

(i)

(ii)

Answer:

Given expression is

Sum of odd terms

And the sum of even terms,

Now

Similarly

Multiplying eq. (i) and eq. (ii), we get

Hence

(ii)

Hence,

Question 16:

If occurs in the expansion of , prove that its coefficient is

Answer:

Given expression is

General terms,

If occurs in

Then

Hence, the coefficient of