SOLUTION: I need help with this problem. I need to solve for a: S= n/2[2a+(n-1)d] Thank you for your help

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Question 165230: I need help with this problem.
I need to solve for a: S= n/2[2a+(n-1)d]
Thank you for your help
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
S= n/2[2a+(n-1)d]
=n/2[2a+dn-d)
=(2na+n^2d-nd)/2
.
Ed