Can someone help me on a few questions which I got stuck on and show me how you got the answer?
1. Evaluate: Sigma sign n on the top, 1 underneath then in the middle 2r-7.
2. The first term of an aritmetic series is 14. The common difference and the sum of the first n terms are both -6. Find n.
3. The first three terms of an arithmetic series are 2x+1, 3x+2 and 5x-1. Find x.
Thanks in advance