Answer:
see below
Step-by-step explanation:
Try j=1 and j=2 in each of the series expressions to see which ones work.
A: 1/3(1+1) = 2/3 ≠ 1 . . . . first term doesn't match
B: 3^(1-1) = 3^0 = 1 . . . . first term matches;
3^(2-1) = 3^1 = 3 ≠ 1/3 . . . . .second term doesn't match
C: (1/3)^(1-1) = 1 . . . . . . . first term matches
(1/3)^(2-1) = (1/3)^1 = 1/3 . . . second term matches
D: (1/3)(1) +1 = 4/3 ≠ 1 . . . . . first term doesn't match
___
The third choice is a summation that matches the given series expression.
