Help with math final exam homework

16. 4, 16, 64, 256, …..   A. Find the tenth term, a10 B. Use summation notation to write the sum of the first ten terms.   C. Use the Sum of Arithmetic or Geometric Sequences formulas (page 666) to find S10, the sum of the first 10 terms. 

Parts A and C are good. Part B is almost there --it is intended to give you practice in using the summation notation for a specific sequence. You would need to write in the actual general rule for this particular sequence (instead of the generic "an ") there after the sigma.