Question

5. Find the sum of the first 35 terms of the arithmetic sequence when a = 5 and d = 4

Answer 1

Answer:

The sum of the first 35 terms of the arithmetic sequence when a = 5 and d = 4 is 2555.

Step-by-step explanation:

Given:

a = 5

d =  4

To Find :

The sum of first 35 terms of the arithmetic sequence  = ?

Solution:

Step 1 : finding the 35th term

$a_n = a_1 +(n-1)d$

$a_35 = 5 +(35-1)4$

$a_35 = 5 +(34)4$

$a_35 = 5 +136$

$a_35 = 141$

Step 2: Finding the sum of first 35 terms

$S_n = \frac{n(a_1 +a_n)}{2}$

Substituting the values

$S_n = \frac{35(5+141)}{2}$

$S_n = \frac{35(146)}{2}$

$S_n = \frac{35(146)}{2}$

$S_n = \frac{5110)}{2}$

$S_n = 2555$