# NCERT Class 11-Math՚s: Chapter – 8 Binomial Theorem Part 7 (For CBSE, ICSE, IAS, NET, NRA 2023)

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**Question 10**:

If the coefficient of second, third and fourth terms in the expansion of are in A. P. Show that .

**Answer**:

Given expression are in A. P. , show that

Coefficient of second term

Coefficient of third term

and Coefficient of fourth term

As the given condition, and are in A. P.

Hence proved.

**Question 11**:

Find the coefficient of in the expansion of .

**Answer**:

## Long Answer Type

**Question 12**:

If is a real number and if the middle term in the expansion of is , find .

**Answer**:

Given expression is

Number of terms

Middle term

Now

Hence, the required value of

**Question 13**:

Show that the middle term in the expansion of is

**Answer**:

Given expression is

Number of terms (odd)

Middle term

General Term

Hence, the middle term