Find the sum of the first 8 terms of the sequence. Show all work for full credit.

1, -3, -7, -11, ...

Question

Find the sum of the first 8 terms of the sequence. Show all work for full credit.

1, -3, -7, -11, ...

anonymous · Answer

Do you notice the pattern?

anonymous · Answer

Could you say what the next term is?

anonymous · Answer

here a=1, d= -3-1=-4, n=8
since$$s_n=\frac{n}{2}[2a+(n-1)d] \rightarrow s_8=\frac{8}{2}[2\times 1+(8-1)(-4)]$$
$$=4[2+7(-4)] =4[2-28] =4[-26] =-104$$

anonymous · Answer

Seriously, bro?

anonymous · Answer

Yes..

anonymous · Answer

Giving a student the answer almost never results in learning. So if you state the answer instead of leading them to find it on their own, your "teaching" is worthless.

anonymous · Answer

And in this case it nullifies others' efforts at actually teaching.

ybarrap · Answer

This is called an arithmetic series. The solution is easy to find when you see the pattern as @SmoothMath indicates. This will be very helpful: http://en.wikipedia.org/wiki/Arithmetic_series

anonymous · Answer

haha thanks guys, I appreciate the help @SmoothMath @dpasingh

anonymous · Answer

read this....it explains well http://www.regentsprep.org/Regents/math/algtrig/ATP2/ArithSeq.htm