SOLUTION: Write 2 - 4 + 8 - 16 + ... + 128 using sigma notation.

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Question 396669: Write 2 - 4 + 8 - 16 + ... + 128 using sigma notation.
Found 2 solutions by ewatrrr, CharlesG2:
Answer by ewatrrr(10682) About Me  (Show Source):
Answer by CharlesG2(828) About Me  (Show Source):
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Write 2 - 4 + 8 - 16 + ... + 128 using sigma notation.

sum%28+-1%5E%28n%2B1%29%2A2%5En%2C+n=1%2C+7+%29
n = 1 --> -1^(2) = 1, 2^1 = 2, 1 * 2 = 2
n = 2 --> -1^(3) = -1, 2^2 = 4, -1 * 4 = -4
n = 3 --> -1^(4) = 1, 2^3 = 8, 1 * 8 = 8
...
n = 7 --> -1^(8) = 1, 2^7 = 128, 1 * 128 = 128