# Question 11 and 12, Exercise 4.1

Solutions of Question 11 and 12 of Exercise 4.1 of Unit 04: Sequence and Series. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan.

## Question 11

Find the indicated term of the sequence: $a_{n}=4 n-3; a_8$.

** Solution. **
Given
$$a_n = 4n - 3.$$ Then
\begin{align*}
a_8 &= 4(8) - 3 \\
&= 32 - 3 \\
&= 29
\end{align*}
Hence $a_8 = 29$.

## Question 12

Find the indicated term of the sequence. $a_{n}=5 n+11 ; a_{9}$

** Solution. **

Do yourself.

### Go to