Question

solve this sum ...... ..... ....​

Answer 1

sum of 6 elements is 102

Answer 2

The Question is,

Let Sn be the sum of the arithmetic progression. If the first value is 7 and the common difference is 4, determine the sum of first six elements.

Solution:

a = 7

d = 4

$sum = \frac{n}{2} (2a + (n - 1)d)$

$= \frac{6}{2} \times (2 (7) + (6 - 1)4)$

$= 3 \times (14 + 20)$

$= 102$

The sum of six elements of an A.P. is 102