Question

find S10 of 1+7+13......
with
explanation​

Answer 1

Answer:

This is an Arithmetic sequence because there is a common difference between the numbers -1: -7: -13: -19: Therefore d= -6

Use the formula for the sum of an arithmetic sequence:

S 10 = n/2 ( 2a + (n - 1)d

S10 = 10/2(2(-1) + (10 - 1) ( -6))

S10 = 5 (-2 + (9) ( -6))

S10 = 5(-2 + (- 54)

S10 = 5 ( -56)

Therefore S10 = -280