HELLPPPP PLEASE !!!! When finding the sum of the arithmetic sequence 4+1+-2+-5+-8+-11 you will have a step of work that contains the number -3. Use complete sentences to describe how the -3 was calculated and what it means

Question

campbell_st · Answer

well you need to find the common difference   

so compare terms 

$$a_{2} - a_{1} = -3.... a_{3} - a_{2} = -3$$

so by comparing terms you find the common difference   d = -3 so the series is arithmetic.

and you have 6 terms where the 1st is 4 and the last is -11. 

then 

$$S_{n} \frac{n}{2}[ a + l] $$

where a = 1st term, l = last term and n = number of terms. 

substitute your given information and evaluate to find the sum

anonymous · Answer

omg thank you!! i a finding the sum now can u give me a minute to figure it out

anonymous · Answer

and tell me if thats correct @campbell_st

anonymous · Answer

is it 7 im confused???

anonymous · Answer

heloooooo @campbell_st please help

anonymous · Answer

oh nvm thank you

anonymous · Answer

No