Ineed with this question someone and explain. find the sum of the first twenty-seven terms of an arithmetic series whose first term is -8 and the sum of the first seven-term is 28.

The sum of the first twenty-seven terms is 1,188

Step-by-step explanation:

we know that

The formula of the sum in arithmetic sequence is equal to

where

n is the number of terms

a1 is the first term

d is the common difference (constant)

step 1

Find the common difference d

we have

n=7

a1=-8

S=28

substitute and solve for d

step 2

Find the sum of the first twenty-seven terms

we have

n=27

a1=-8

d=4

substitute

answer: all the values are within because it has a pattern that repeats from -6 to 4.

good luck!