+ Page view A Read aloud T Add text Draw (20 pts) 12. (a) An arithmetic sequence has first term a = 50 and common difference d = 4. Determine an equation for the general term a,, , and use it to find the 100" term. Find the sum of the first 1000 terms of this sequence. 100 1000 (b) A geometric sequence has first term a = 5120 and common ratio r = Determine an equation for the general term a,, , and use it to find the 6th term. Also, find the sum of all the terms of this sequence, IM : a, = a =