Question 1025555

Find the sum of the first 8 terms of the sequence. 
1, -3, -7, -11, ...
<pre>This is an AP with d (common difference) = - 4, and the 1<sup>st</sup> term, or {{{a[1] = 1}}}.
Use the formula for the sum of an AP: {{{S[n] = (n/2)(2a[1] + (n - 1)d)}}} to get the sum of the 1<sup>st</sup> 8 terms. By the way, n = 8