Question

Write the related series for the finite sequence –7, –10, –13, . . ., –22. then find the sum.–7 + (–10) + (–13) + (–16) + (–19) + (–22) = –87
–7 + (–10) + (–13) + (–15) + (–18) + (–22) = –85
–7 + (–10) + (–13) + (–14) + (–18) + (–22) = –84
–7 + (–10) + (–13) + (–17) + (–20) + (–22) = –89

Answer 1

I would say the last one, -7+(-10)+(-13)+(-17)+(-20)+(-22)=-89 , it seems the most reasonable since you go up by -3, hope this is correct and helps if not i apologize 

Answer 2

Answer: $-7+(-10)+(-13)+(-16)+(-19)+(-22)=-87$

Step-by-step explanation:

Given finite sequence : -7, -10, -13, . . ., -22.

Difference between first and second term=$-10-(-7)=-10+7=-3$

Difference between second and third term =$-13-(-10)=-13+10=-3$

Hence, the common difference = -3

The next term after -13 =$-13+(-3)=-13-3=-16$

The next term after -16 =$-16+(-3)=-16-3=-19$

The next term after -19 =$-19+(-3)=-19-3=-22$.........which is the last term of the sequence.

Now, the sum of the given sequence =$-7+(-10)+ (-13) + (-16) + (-19) + (-22)$

$=-7-10-13-16-19-22= -87$